Questions & answers on troubleshooting heating boiler pressure & temperature gauges:

Frequently-asked questions about gauges found on hot water (hydronic) heating boilers, steam boilers, and other heating equipment can help diagnose & repair operating problems with these systems.

This article series provides an inspection and repair guide to Heating System Gauges: Pressure and Temperature Gauges on Heating Boilers. We also describe the normal operating pressures for hot water hydronic heating boilers and for residential steam boilers.

Heating System Pressure Gauges & Normal Steam or Hot Water Boiler Pressure Ranges

These questions & answers about pressure and temperature gauges found on heating boilers were posted originally at GAUGES ON HEATING EQUIPMENT - you will want to review that data too.

On 2019-10-04 by (mod) - choosing an accurate low-range pressure gauge for residential steam heating systems

MIke

THank you for the follow-up about gauge tolerance for over-pressure; that will help other readers.

On 2019-09-24 by Mike

correction - rapture rating is 7.5 psi in this case (250% of 3 psi).

On 2019-09-24 by Mike

Just spoke to Kodiak and they told me the following is true for their KC25-3# gauge.

- over-pressure rating (pressure beyond which gauge would get damaged) is 25% or the reading so in this case it would be: 3.75 psi.

- rupture pressure rating (pressure where it would blow out and flood the area) is 250% of the reading - in this case it would be 7.7 psi.

On 2019-09-23 by (mod) -

YOu'd need to ask Kodiak; they sell gauges under their own brand as well as gauges produced by other manufacturers; but none of the online data sheets for the KC25 mention a maximum safe pressure exposure. I would not assume that a low pressure gauge that is rated to read up to 3 psi can tolerate much higher pressures safely.

On 2019-09-23 by Mike

Wonderful - Thank you for the idea.
I just wonder how much pressure abuse such 3 PSI would take before blowing out and flooding the building - hopefully at least 30 PSI (or at least below 15 PSI relief valve).

On 2019-09-23 by (mod) - choosing a low-range scale boiler pressure gauge to read with more accuracy

kodiak-low-range-pressure-gauge-kc25-3

Here is a low pressure analog water pressure gauge operating in the 0-3 psi range, the Kodiak Controls KC25-3# (Under $30. U.S.)

from
Kodiak Controls, Inc.
Phone: 630-629-3733
Fax: 630-629-3544
kodiak@kodiakcontrols.com

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website. We very much welcome critique, questions, or content suggestions for our web articles.

Watch out: I would not install a pressure gauge on a system whose operating and safety controls could permit the system pressure to ever exceed the pressure gauge maximum working pressure range - the risk is that you blow the gauge, flood the building, or blow up the boiler.

I like that idea of a more-accurate pressure gauge too; it's not easy to find a gauge reading just in the low range; the market is dominated by the 0-30 psi range products.

There are digital pressure gauges that are (or claim to be) accurate in low-range but they're pricey, around $100. U.S.

Kodiak Controls offers a low pressure analog pressure gauge KC25-3# in the 0-3 psi range for under $30.- shown in the photo above.

The ProSense digital pressure gauge DPG1-15 is +/- 5% accurate and can be obtained in the 0-15 psi range - shown below.

On 2019-09-23 by Mike

Thank you for your prompt answer Dan

That makes sense. Looks like I am going to replace that 30 PSI gauge with 5 or 10 PSI gauge for more accuracy and easier reading in my boiler.
My gauge currently doesn't work - either is damaged or the pigtail might be clogged - but this will be the opportunity to swap it to a better gauge.
Thanks a lot again.

On 2019-09-23 by (mod) - If the pressure of the steam boiler shouldn't be above 2 PSI, why do I see pressure gauge scaled out all the way to 30 psi in this picture ?

Thanks for asking, Mike.

There are two parts in my answer to why you see a pressure gauge scaled all the way up to 30 psi on a residential steam boiler that should not normally operate above 2 and usually just around 0.2 psi.

1. The black ROUND gauge in the photo whose scale runs between 0psi and 30 psi is NOT the CONTROL it is a generic PRESSURE READING gauge reading boiler pressure.

And its 5 tick marks between 0 and 5 allow a homeowner or service technician to see that the pressure is indeed in the very low end of the proper range - under 2 psi means that the gauge won't run much above that first tick mark.

2. The gray rectangular gauge at the right of the photo (which is an enlargement of a photo given earlier on this page) is the PRESSURE CONTROLLER for the residential steam boiler. You will see that the scale on its gauge runs from 0 to just 9 psi, and it gives very clear reading tick marks along the left indicating 0.1 0.2 (no number) 0.3 0.4 (no number) and 0.5.

At higher pressures you'd read the same control along its right hand scale that runs from 0.1 up to 9 psi.

General Remarks about Pressure Control and Pressure Gauge Scales and Ranges

The reason you might see a pressure gauge or control that scales above the proper and safe pressure for a residential (home) steam boiler (or some other specific applicatio) is simply that the manufacturer has designed the device for use on a wider range of equipment and systems. For example some commercial / industrial steam boilers may run at considerably higher pressures.

An example of high pressure steam boilers and their operation is at STEAM BOILERS GENERATORS CONTROLS, PRATT inspectapedia.com/heat/Steam_Systems_Pratt_Milster.php

However the manufacturer's recommended pressure for a mountain bike might be just 25 psi

Still you've asked an important question in another regard, Mike. SOME pressure reading gauges or pressure controls may be inaccurate at the low end of its scale if the device is designed specifically for high pressure range operation.

For example I would not use a gauge scaled for high pressure refrigerant to measure the low side pressure because the gauge may be inaccurate in that range.

On 2019-09-23 by Mike

If the pressure of the steam boiler shouldn't be above 2 PSI, why do I see pressure gauge scaled out all the way to 30 psi in this picture ?

On 2019-03-22 by (mod) -

Anon

I'm confused, which is itself confusing as I'm the one writing a reply to your question. The operating pressure inside or of a steam boiler used to heat a building has nothing to do with the flow rate or "pressure" of hot water supplied to sinks, tubs, showers in a building. Typical residential steam boiler internal pressure is less than 1 psi.

However your landlord may have given a confused explanation of why hot water supply pressure to plumbing fixtures is less.

For example, she could have resticted hot water flow rate to the building tenants simply by partly closing a main hot water supply valve (I am guessing as I have no idea what she did). One would do that to slow the rate of use of hot water as a way to reduce the cost of supplying hot water to a building.

On 2019-03-22 by Anonymos

Landlord lowered hot water pressure due to steam furnace constantly running. Now there’s not enough hot water pressure to use my dishwasher. Does this make sense, because it doesn’t to me. I’ve been here for 4 years and this never happened before. What’s my landlord up to?

On 2019-03-22 by (mod) - steam boiler pressure independent of building hot water supply pressure to plumbing fixtures

Anon

I'm confused, which is itself confusing as I'm the one writing a reply to your question.

The operating pressure inside or of a steam boiler used to heat a building has nothing to do with the flow rate or "pressure" of hot water supplied to sinks, tubs, showers in a building.

ypical residential steam boiler internal pressure is less than 1 psi.

However your landlord may have given a confused explanation of why hot water supply pressure to plumbing fixtures is less.

For example, she could have resticted hot water flow rate to the building tenants simply by partly closing a main hot water supply valve (I am guessing as I have no idea what she did).

One would do that to slow the rate of use of hot water as a way to reduce the cost of supplying hot water to a building.

On 2019-03-22 by Anonymos

Landlord lowered hot water pressure due to steam furnace constantly running.

Now there’s not enough hot water pressure to use my dishwasher. Does this make sense, because it doesn’t to me. I’ve been here for 4 years and this never happened before. What’s my landlord up to?

On 2018-01-31 by (mod) - Burnham Series 2 (model B) boiler TPR valve leaks

yes you could have a leaky pressure relief valve, or there could be an external cause such as water hammer.

On 2018-01-29 by Ted Sillox

Hello, I have a Burnham Series 2 (model B) boiler around 17 years old. I replaced the old sidebar domestic water heater and also replaced the backflow valve, the feed pressure valve, the relief pressure valve, the bladder expansion tank and rebuilt the Spirovent over the tank.

Boiler pressure cold is around 15psi and rises to around 23psi when firing. I notice that there is a discharge from the relief pressure valve every morning but when I observe the boiler the pressure never comes close to 30psi. Could I have a new pressure relief valve that is defective? Thanks, Ted

On 2018-01-02 by (mod) - boiler not heating up

Marla,

As I'm traveling I must be brief

In the ARTICLE INDEX

See NO HEAT, BOILER

For diagnostic steps you can take before having to call for repait

On 2017-12-30 by Marla

I have a new Williamson GSA 125 S P - set at 72 degrees and the heat in the house is very low . I am very frustrate

On 2017-10-01 by Dave

I have an old (circa 1960) G series hot water boiler. The square pressure/temperature gauge just started leaking. where can i get a replacement?

On 2017-02-12 by Don B

The pressure gauge is located on the return piping before circulating pump and it reads approx 12-14 psi when pump starts up then slowly drops to zero when pumps shuts down. Boiler pressure gauge stays constant at 22psi.

Supply line goes from boiler thru expansion tank and scoop to zone valve manifold. My question is, if it's a closed loop how can that gauge be zero should it not be same as boiler. Forgive me I'm just a carpenter!

On 2017-01-22 by (mod) -

Interesting, Don.

I am not sure exactly where on the hot water circuit your pressure gauge is installed.

In general, the boiler pressure will range between 12 psi cold and somewhere in the high 20's psi when the boiler is at its hottest - if measured right at the boiler.

Measuring pressure on the inlet side of a circulator pump may show lower psi because on the inlet side the pump is in effect "sucking" on the hot water pipe, causing pressure to drop on the pump's inlet side.

Measuring in that same location when the circulator has stopped might indeed register a low or even 0 psi if a check valve (typically a Flo-Control valve found on each zone where hot water leaves the boiler) is installed and working. T

hat valve closes to keep hot water from circulating through the system by natural convection (circulator is off) when there is no call for heat.

Search InspectApedia.com for FLOW CONTROL VALVE to see details.

On 2017-01-21 by Don B

I have a pressure gauge before circulating pump and one on the boiler. The boiler reads 20 psi, when circulating pump is running gauge before circ pump reads 12 psi but when boiler shuts down gauge before circ pump drops to zero but boiler gauge remains at 20 psi?

On 2016-12-22 by (mod) - removed the steam vents - now no heat

LZ:

Watch out: removing the vents will indeed let steam rise into radiators if they're not otherwise blocked, but once hot steam starts shooting out of the vent mounting opening you can get burned or have a difficult time replacing the radiator vents.

I would look for a system steam trap or control between the boiler and the first cold radiator.

On 2016-12-22 197 by (mod) -

Re-posting on new page

LZ said:

one pipe steam system. not super efficient but worked ok. somehow a couple days ago, radiators stopped heating up. checked the steam main pipe, it is hot.

means there is steam came out from the boiler. and all the branches are hot. then checked all radiator, valves are fully open. finally decided to twisted vents off, but still no steam comes out.

seemed like the steam in the main pipe magically disappeared somewhere before it reach any radiator... can any expert here take a good guess what's going on? thx.

Question: a few questions about commercial / power plant steam generators

1) How to size the safety valve for a boiler with no stamp?

2) What are the overall conditions responsible for the damage of superheater coils?

3) Why is deaerated water not used in boiler at the time of boiler hydraulic testing?

- Mohnish

Reply:

Mohnish:

Size or rating of the pressure/temperature relief safety valve on steam boilers & missing data tags

If the data tag identifying the safety valve has been lost, and considering that this is such an important safety device, and considering the importance of installing a valve of adequate capacity, I'd just replace a valve that was in question for any reason whatsoever.

We're talking about a residential part price of $20. U.S. (or less).

In some jursidictions even on residential steam heating boilers and certainly on a commercial or power plant steam generator in particular, I wouldn't be surprised if regulations and maintenance guidelines would view a missing steam boiler pressure/relief valve data tag as a safety violation.

Also see RELIEF VALVE, TP VALVE, STEAM BOILER

Superheater coils on steam boilers, sources of damage

I presume you are referring to super heater coils that are used in a steam-heat system boiler to generate saturated steam. The super heater coils are specially used in Boilers of Power plant. These are not residential heating system components, and with respect, are beyond our expertise.

In my OPINION an important consideration is to assure that the proper safety pressure/relief valves are mounted at the proper locations and are in good working condition on superheater coils as well.

SeeReferences or Citations for superheater coils and super heater coil damage. [1]

Use deareated water in steam boilers during testing?

That question too is not pertinent to residential steam systems. Deareated water is water used in commercial or power generating boilers from which dissolved oxygen or other gases is removed to avoid corrosion in the system.

(Oxygen and other gases are removed during deaeration to a level as low as feasible - it won't quite be to zero. typically oxygen is removed down to about 7ppb during deaeration of water for steam systems. [2]

OPINION: it may seem reasonable to test a steam generating boiler with deaerated water, arguing that you're trying to duplicate the in-service condition.

However I speculate that

• The corrosive effects of a brief hydraulic pressure test of a steam generating system are perhaps very low or even below measurement thresholds, as compared with in-service use water, perhaps moreso if performed at low temperature
• The focus in steam generating boiler testing is on pressure tolerance and leak detection over a short interval nothing like the in-service life over which hot water in a steam generating boiler, if not deaereated, would be expected to have very corrosive effects.

Take a look at Steam: Its Generation and Use for details. [3]and see our articles on residential and light commercial steam boilers beginning

at STEAM HEATING SYSTEMS.

Question: relief valve popped - did the repair person do something wrong?

(Feb 27, 2014) Kevin said:
I had no heat and my oil nozzle was replaced on my boiler, less than an hour later there is water gushing out the pipe that is on the tank that holds the water. I was told the relief valve popped due to the pressure, did The person that worked on the boiler fail to do something when restarting the boiler?

Reply:

Kevin,

I don't have a clear idea of what happened to your system nor what is "the tank that holds the water".

But if the water spillage that you saw was coming out of a pressure/temperature relief valve, that is indeed a response to an unsafe pressure OR an unsafe temperature in the heating system (depending on the type of relief valve they're called TP valves or Temperature & Pressure Relief Valves).

JUST changing an oil burner nozzle would not normally cause a heating system over-pressure condition. An over-sized nozzle (burning too much oil, making a too-big flame) might overheat a boiler but the boiler's primary control or limit control ought to turn off the burner in that case.

And if the oil burner adjustment were improper, still the boiler's primary control unit has a high-temperature limit that is intended to shut off the burner when temperatures exceed the HIGH LIMIT.

Therefore it sounds as if there was a different problem. Some possibilities include:

- the boiler's expansion tank was waterlogged (most likely)

- the primary control high temperature limit was improperly set too high

- the relief valve failed or was left open manually

- something else I can't speculate on as I don't know a thing about your system

Keep us posted, what we learn will help other readers.

Question: gushing water sound through heating pipes

Mar 29, 2014) Anonymous said:
there is sounds of water gushing through all the pipes that run through the baseboard heaters,sometimes its really load.

WHY? Mar 29, 2014) Anonymous said:

Sorry I have a boiler furnace and the hotwater that runs through the baseboard pipes sometimes sounds as waters GUSHING through all the pipes...

its very loud at times that my daughter lives right next door where the boilerroom is can hear it too...WHY??? ment to put loud not load... angelafernan1972@gmail.com

Reply:

Sounds like air in the heating pipes. See

AIR BLEEDER VALVES and

also AIR SCOOPS PURGERS SEPARATORS

Question: standard temperature and pressure for heating systems

(Apr 12, 2014) jonathan said:
What is the standard temperature and pressure ranges

Reply:

Jonathan, the normal temperature and pressure ranges for heating equipment vary by type: hot water vs. steam

You can read these in GAUGES ON HEATING EQUIPMENT under the headings

What Are the Normal Hot and Cold Operating Pressures of Residential Hydronic (hot water) Heating Boilers?

and

What Are the Normal Hot and Cold Operating Pressures of Residential Steam Heating Boilers?

If any of that is unclear please just ask and I'll answer further.

Thanks

Daniel

Question: intemittent problem with pump won't start

(Dec 15, 2014) Bruce said:
We have a hydronic heat system intermittent problem where the cartridge recirc.pump does not start when the thermostat calls for heat.

The fan comes on and we have plenty of hot water but the pump does not send hot water to the air handler.

If I turn the system off for a couple of hours, then back on, it will work perfectly until the next random malfunction. I replaced the Taco pump but that was not the problem. I was finally able to determine that no power is being sent to the pump during the malfunction.

The relay is working (there are 2 and I have swapped them to test , one runs the water heater) so it seems that the problem is between the relay and the pump?

This is driving us crazy and to the poor house! We have had the HVAC guys out several times to fix it but of course it works perfectly and they can not find any malfunction, then in the middle of the night we wake up freezing! Any suggestions would be appreciated! Thank you. Bruce

Reply:

Bruce,

From what you describe I'd be looking for a loose wire connection or damaged wiring either between the circulator relay control and the pump or between the thermostat and the relay.

The next time the circulator doesn't start, tell me what happens if you

- tap on the relay control box

- push the relay closed

- remove the thermostat wires and jump those terminals at the relay control

Question: ok to run boiler if water pressure is low?

(Dec 31, 2014) Ronald said:

Is it safe to still run the oil boiler while the water pressure is so low, just a trickle of water at this time.

Reply:

Ronald

If the boiler or heating system is full of water and not leaking it should be ok to run.

Watch out:  If boiler water is Lost it can't be run without damage.

Assuming you have hot water heat, if just some water were lost you'd probably note that the boiler was running but some baseboards or radiators are cold.

Question:

Apr 29, 2015) Anonymous said:
Bill: How do I increase the water temperature in the shower coming from a one pipe steam boiler?

Reply:

Search InspectApedia for "tankless coils" if that's how you're making hot water.

Question:

May 29, 2015) Judi said:
We have a Saturn / Kerr.

even when our heat is turned down, we have heat spewing from the radiators.

and we find it hard most times to get real hot water from our taps in kitchen bad bathroom......zone valves have been replaced many times , last time we called them out they saw no problem.

however my oil bills are atrocious! Very frustrated

Reply:

See HEAT WON'T TURN OFF

Question: Tapping noises from Weil McLain hot water "furnace"

(Dec 15, 2015) Stan Eaton said:
Hot water furnace, a Weil McLain is making slight tapping noises when running. Pressure settings get to 45 & 80 respectively.

The tapping seems to come from the aluminum vent above the unit - not the motor or where fire initiates. Do I have a problem ? Contact at .. stanleybeemer@hotmail.com

Reply:

Water pressure in a hot water heating boiler in a residential property is not normally above 30 psi. Something is wrong and if those pressure readings are accurate your system is UNSAFE and should be shut down while waiting for repair.

Also at those pressures the temperature/pressure relief valve should be dumping.

Question: how to fix gurgling noises at the hot water heat baseboards

(Mar 5, 2016) Karen said:
My hot water oil burner heater is gurgling pretty loudly at the baseboards. Also the needle gauge on top reads zero and needle guage on bottom reads 180.

I'm assuming that's the pressure gauge and bottom reading is OK. It's the top reading I'm nervous about. Could someone have forgotten to turn the water back on after servicing the unit?

Reply:

Karen,

Please search inspectApedia.com for AIRBOUND HEATING SYSTEM REPAIR to read about how to purge air from the system. If questions remain just let me know

Question: is 19 psi normal for my New Yorker "furnace" (heating boiler)

(Mar 14, 2016) Matt Stevenson said:

My New Yorker furnace is at 19 psi. It say normal is 40 psi. Answer?

Reply:

Matt

I don't have an answer and am not sure I understand the question. Heating Furnaces are forced warm air heating systems;

Heating Boilers are hot water or steam heating systems. I note that some people use "furnace" loosely for all of these different systems.

Hot water heating boilers normally operate at 30 psi or less when up to full operating temperature or HOT; higher than that will dump at a relief valve.

Hot water heating boilers, WHEN COLD, that is before the burner has operated, may be as low as 12 psi. That's normal.

40 psi sounds wrong and in fact would cause spilling at the relief valve.

Question: how to fix water hammer noise at a Weil McLain gas boiler

(Apr 3, 2016) Anonymous said:

HI, Thank you for the article.

MY Weil McLain gas boiler has water hammer issue and also pressure relieve dripping water issue.

Now I turned off the boiler and also the hot water storage, but I see that it still dripping water, the water pressure reaches 30 pounds, even the water is cold.

Do you know what problem this is?

Reply:

Anon:

Please search InspectApedia for WATER HAMMER DIAGNOSIS to see how to diagnose and cure that problem.

inspectapedia.com/plumbing/Water_Hammer_Noise.php

Indeed water hammer can cause leaks at the relief valve.

BUT

30 psi cold is abnormally high for a residential boiler.

Typically the cold water pressure (boiler is cold) will be 12psi or maybe a bit higher for taller homes. If you verify (using an independent pressure gauge) that the pressure really is 30 psi, then there may be a problem with the water feeder-pressure reducer valve for the boiler

see inspectapedia.com/heat/Water_Feeder_Valves.php

Question: Noisy Kerr water boiler, boiler needs water

(May 29, 2016) charlie said:
My kerr water boiler makes noises getting to temp, it needs water should do that automatic but is not what to do

Reply:

Charlie,

Temporarily you may be able to add water manually opening a manual water feed valve, but it sounds as if your boiler needs service and repair: it may be leaking somewhere (boiler or hot water piping, baseboards, etc), or may be air-bound, as well as needing a repair to the automatic water feed valve. Check for clogged air bleeder valves too as that may explain the air noises.

Question: Dettson Hydra+ buzzing sound

(Oct 16, 2016) David said:
Hi,
I have a Dettson Hydra+ system. When I turn it ON, it makes a loud buzzing sound and nothing seems to work. The pressure seems correct. Any idea about what I should check?
Thanks!

Reply:

David

Watch out: I would turn the system OFF immediately and call for service. It may be something as simple as a failing low-voltage transformer on a control board but buzzing can also be an electrical short that could start a fire.

Search InspectApedia.com for BUZZING NOISE DIAGNOSIS to read more diagnostic suggerstions.

Question: building super says no heat until it's frigid outdoors

(Nov 6, 2016) Anonymous said:
super told me, only get heat if it's extremely frigid outside.

Reply:

Anon

Depending on where you live there are typically rental property laws that include a specification of at what outdoor temperature the building must provide heat to tenants.

Question: no heat

(Nov 24, 2016) Anonymous said:

Pipes from the furnace don't get hot

Reply:

Anon Please search InspectApedia.com for NO HEAT - BOILER to see how to diagnose and fix the trouble.

Question: what are the proper boiler gauge pressure readings?

(Dec 11, 2016) Mike said:
Automatic flow valve to filler boiler (bell/gossett) SET AT 12PSI. On hydronic system gauge on boiler reflects 5 lbs on when boiler is cold.

Should the gauge be reading 12lbs like the flow valve?

Is 5lbs enough pressure for a cold boiler and how high should pressure go when boiler temp. reads 120 degrees or more.

Reply:

Mike, the pressure in standard residential hot water heating boilers in buildings that are no more than 3 stories including basement would be typically 12 psi cold and somewhere under 30 psi when the boiler is hot. 5 psi may not be enough pressure to get heat to upper floors.

Question: radiators just stopped on my one-pipe steam heating system

2016/12/22 LZ said:

one pipe steam system. not super efficient but worked ok. somehow a couple days ago, radiators stopped heating up. checked the steam main pipe, it is hot. means there is steam came out from the boiler. a

nd all the branches are hot. then checked all radiator, valves are fully open. finally decided to twisted vents off, but still no steam comes out. seemed like the steam in the main pipe magically disappeared somewhere before it reach any radiator... can any expert here take a good guess what's going on? thx.

Reply:

LZ:

Watch out: removing the vents will indeed let steam rise into radiators if they're not otherwise blocked, but once hot steam starts shooting out of the vent mounting opening you can get burned or have a difficult time replacing the radiator vents.

I would look for a system steam trap or control between the boiler and the first cold radiator.

How to determine what type of heating system is installed:

Warm Air Heating Systems - Furnaces: If the heat in your building is provided by warm air that flows out of ceiling, wall, or floor air supply registers into the occupied space, or if your heating system uses a water-to-air heating system then the air which warms the living space is probably being delivered through large or small diameter ducts, registers, air filters, and a furnace blower, and the air is being heated by a gas, oil, or electric furnace, or perhaps by a heat pump or a geo-thermal system.

See FURNACE CONTROLS & SWITCHES and for details

see FURNACE OPERATION DETAILS.

Hot Water or Steam Heating Systems - Boilers: 

If the heat in your building is provided by warm or hot metal radiators, heating baseboards containing finned copper tubing, or wall convectors that look like a radiator but contain finned copper tubing, or if heat is provided by flexible rubber, plastic, or metal tubing run in building floors or ceilings, then the warm or hot water circulating in those devices is probably being delivered by piping circulating water heated by a heating boiler, or possibly by a steam boiler or a heat pump or geo-thermal system.

See BOILERS, HEATING

and RADIANT HEAT FLOOR MISTAKES.

If your heating radiators have valves which hiss and let air escape as heat is coming on your heat is probably being delivered in pipes which circulate steam from the steam boiler up through radiators in the occupied space.

See STEAM HEATING SYSTEMS .

This website provides description of all of the major components of hot water or steam heating systems, how to recognize or find each component, what it looks like, what goes wrong, and how to maintain, repair or adjust the component.

On 2012-12-15 by (mod) -

John,

Tap gently on the gauge; if it doesn't drop and work freely it probably needs to be replaced;

Sometimes crud in the boiler water clogs the gauge sensor port but given the time and trouble to remove the gauge to try to clean it, not wanting to do the job twice, I'd replace it.

On 2012-12-14 by John Langley

I have a P/T gauge on my MiniGas MG50 boiler which in a weird condition when I moved in the house: the pressure is around 10 PSI which is in a working condition. The temperature is out of range and the pointer stay out of range and never fall back to work area. D

o you think I can find a way to put(reset?adjust?) it back to the normal position to make it work or need to be replaced? Thank you!

On 2012-09-27 12:56:23.953398 by (mod) -

Ray,

It is usually easy to replace a dial glass and possibly, working carefully, the gauge face and needle, but not the actual dial assembly or indicating gauge mechanism. To do that the whole gauge is replaced.

On 2012-09-27 12:53:51.205937 by (mod) -

Anon, search InspectAPedia for

Flue vent connector

And you will see these are standard dimensioned parts.

On 2012-09-26 y Anonymous

what to do when you can't find a replacement smoke stack relay for an old oil burner for hot water heating

On 2012-02-16 y Ray

The pressure/temperature gauge on my Utica residendial boiler has a large "E" type retaining clip that holds the dial to the 5/8 square brass mounting stem.

Can the dial part be replaced leaving the stem in the boiler?

On 2012-01-21 by Kim

Thanks for the response. There are two gauges-one blue and one red.

They each have two sets of numbers but no where on the dial is the letters PSI. On the blue the higher number is 91 and the lower number is 34. The red dial the higher number is 100 and the lower number 40.

The system has a Taco Cartridge Circulation box and a pump encased. The pump is too hot to touch. There are two water lines coming in the top one has a valve closure and the metal part of the pipe is full of yellowish deposits so much so the shape of the pipe itself is hard to make out. The second line below it is connected to the pump.

That line also has a valve closure. In spring we are told to close both the valves and turn off the call switch.

And of course shut off our thermostat. Last winter the old boiler which had leaked for 2 yrs and never been fixed quit. That boiler was covered in deposit and the technician said the lines were filled with corrosion and that's what killed it. The lines have not been purged. Their fix was to replace that part which this winter needed priming.

The technician was a new guy he opened it up, claimed he primed it, and was in and out in 15 minutes. Before he primed it the pump was making noises and the gauges both read past 120 in the big numbers.

My belief is that if they haven't purged the lines of the deposits that this problem will never be solved. The first technician that serviced it and stated it needed purging was the same man who installed it 15 years ago. He claimed at that time the system had never been maintained.

On 2012-01-21 by Anonymous

Anon, I'm only speculating, with so little information about what your heater gauges are reading and how your radiant floor heat was installed.

Typically one temp gauge may give the boiler temperature and the other the (lower) temperature of water that is circulating through the radiant heat floor tubing.

There may also be a gauge showing temperature in and temperature out of the radiant floor system. If your heat is not sufficient the first question that occurs to me is - has this always been the case (suggesting a design or installation problem) or has something changed ( indicating a repair or maintenance issue).

A noisy pump and having to "re prime it" suggests the system could be airbound - which would prevent hot water from circulating. Air may have entered the system and not been adequately purged during boiler replacement.

Corrosion visible on the exterior of heating piping does not quite tell me the condition of the piping interior nor if it needs replacement.

On 2012-01-21 by Anonymous

I live in an apartment building with radiant heated floors. In our unit we have a stand alone boiler.

The boiler has two gauges. One reads 80 and one reads almost 100. Our temp set on thermostat is 85 and our unit never gets warmer than 67 degrees. We use space heaters to compensate.

The boiler and pipes are corroded. The first boiler leaked they replaced it with this one. The pump or something on this replacement started making noise this past Oct. so a technician came in and primed it.

The previous technician stated that there was so much corrosion in the lines the place needed a complete overhaul. He has since retired.

My landlord gets by with this because they don't think we'll ever find out the answer to my previous question. I have taken pictures. I can't call anyone in town because we have but one plumber-he gets all this places emergency no heat calls so he isn't going to answer me honestly.

He is making a fortune. I think our boiler is defective. Our floors aren't even warm. Can you tell me what those gauges are supposed to read? I'd be happy to send you photos. Thanks in Advance,Kim

On 2011-12-19 by (mod) -

Mohnish, to obtain more space I've moved our reply to the FAQs section above.

On 2011-12-19 by Anonymous

Joseph: thank you for the nice note. We work continuously on website content accuracy and welcome questions and suggestions as well. Daniel

On 2011-12-19 by Joseph Wojciechowski

Thank you for your DIY instructions pertaining to the pressure temperature gauge replacement.

On 2011-12-19 by Mohnish

1) How to size the safety valve for a boiler with no stamp?

2) What are the overall conditions responsible for the damage of superheater coils?

3) Why is deaerated water not used in boiler at the time of boiler hydraulic testing?

...

Continue reading at GAUGES ON HEATING EQUIPMENT - topic home, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see these

Heating System Gauge Articles

• BOILER CONTROLS & SWITCHES
• BOILERS, HEATING - home
• EXPANSION TANKS
• GAUGES ON HEATING EQUIPMENT
  • BOILER GAUGE REPLACEMENT
  • GAUGES, HYDRONIC BOILER
  • GAUGES, STEAM BOILER
  • OIL TANK GAUGES
  • SIGHT GLASS, STEAM BOILER
  • SIGHT GLASS REPLACEMENT
  • SIGHT GLASS & HYDRONIC HEAT LOOPS on STEAM SYSTEMS
• PRESSURE & TEMPERATURE SETTINGS, CONTROLS
• STEAM BOILER PRESSURE
• STEAM BOILER TEMPERATURE
• STEAM BOILER SIGHT GLASS
• STEAM HEATING SYSTEMS & CONTROLS

Suggested citation for this web page

BOILER GAUGE FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---