Heating Boiler Repair FAQs #2

Q&A about heating boiler temperature & heat delivery

Boiler Too Hot FAQs

Diagnose too-high heat in the boiler

I have a Weil-Mclain oiled fired boiler for heat and the temperature started going to over 200 degrees with a high temp light coming on . What may be the cause ? On 2019-01-12 by gary

Reply by (mod) -

Gary

Watch out: What you describe is unsafe and risks a BLEVE explosion.

I suspect a bad aquastat or bad aquastat-sensor, but of course you need to first confirm that the aquastat itself is set to 200F or lower.

First see AQUASTAT SENSOR PROBE HEAT CONDUCTING COMPOUND 

If cleaning and properly-installing the temperature sensor doesn't fix the problem, and provided that your aquastat temperature settings are proper (HI at or below 200F), then the aquastat or sensor need to be replaced.

To check your settings, see AQUASTAT HI LO DIFF SETTINGS

Watch out: also, if your boiler temperature exceeds 200F then the boiler's temperature / relief valve should have opened to relieve pressure - if that's not happening I worry that the relief valve may be unsafe.

See RELIEF VALVE, TP VALVE TEST

Our oil fired heat is not working - overheating - showing a "thermometer" symbol

My oil heating is not working. the thermometer symbol is lit up on the boiler - Margaret 10.21.11

Reply: heating boiler thermometer symbol shows and boiler is OFF. Check the Aquastat then call for repair.

Margaret, it sounds as if a diagnostic light is lit on the primary control of your heater - it's time to call a service technician.

My best guess at the meaning of that little thermometer symbol is that your boiler system is overheating (over 200°F) or that its internal pressure is too high (over 30 psi) and has been shut off by a safety control.

Some AI sources suggest that you bleed air from the system but in my OPINION that's not useful nor likely to be accurate.

At AIR-BOUND HEATING SYSTEMS - home - we explain that air in the hot water heating sytem pipes, baseboards, or radiators, can lead to a cold or not warm-enough heater but it wouldn't explain an over-pressure nor over-temperature condition.

If you are comfortable doing so you can look at the temperature settings on your boiler's primary control, it's aquastat, to be sure that no one has simply turned a temperture dial up too high.

See AQUASTAT HI LO DIFF SETTINGS for how to do that.

Unfortunately you didn't give me any other infomation about your heating system; though you might get some help by following the basics at

• NO HEAT - BOILER

- making sure you have electrical power & fuel and that the thermostat is calling for heat.

The user's manual for your boiler, perhaps it's a Valliant or a Viessmann thsat use a thermometer symbol as an indicator on a digital display.

If you don't already have the user's manual for your boiler, see

• MANUALS & PARTS GUIDES - HVAC - home - Master Index to All Brand Names & HVAC manuals, wiring diagrams, installation and repair guides

Abnormal pressure & leaking Steam at Steam Boiler? Is my steam boiler too hot?

National Radiator steam boiler, converted from coal to gas, also makes hot water - is hissing, what's wrong?

I have ancient National Radiator Boiler - was coal, now gas. Hot water.

This morning, the boiler turned on and I could hear loud hissing.

The copper pipe that mixes with the cold water (return?) was emitting so much steam from a vent pointed toward the cellar rafters, it was actually dripping on the boiler.

The old steam gauge? Which says National Radiator, is usually just about 1; today it went up to almost 4.

The Honeywell gauge seemed to stay where it belonged.

The water in the sight glass surged, then returned to normal level.

I lowered the temperature, hoping to stop the steam, and eventually the boiler turned off.

The pipes that hold hot was were too hot to touch.

After about 1/2 hour, I placed an ordinary house thermometer on the hot water pipe and it registered 120 which is the highest it could go. I'm sure it was hotter than 120.

Can you tell what is wrong by what I am trying to ask? Does anything sound dangerous? The boiler is probably more than 80 years old.
Thank you. On 2017-05-06 by Phil R

by (mod) - steam leaks at the boiler (except at steam vents) are abnormal and unsafe

Phil

Steam boilers "boil" water to make steam so it's normal for the water to be at 212°F (at sea level, a bit less at higher elevations).

And hearing hissing as a boiler heats up could also be the normal sound of hot water being heated in a boiler.

But we don't expect to see steam leaking out anywhere except for the noise of steam escaping at a steam vent. You can see a steam vent safety devicve at the top of the antique National Radiator steam boiler in our image above.

It sounds as if your steam heating boiler maybe overfilled, that is too high water level which would be due to a problem with an automatic water feeder or overfilling manually.

Or secondly the boiler maybe surgeon which could have a number of causes including debris or crud in the boiler itself.

I'm going to give you links for three articles you should read. Then you'll want to call your heating service tech.

SIGHT GLASS, STEAM BOILER 

CHEMICAL TREATMENTS, BOILER

STEAM BOILER FLOODING / SURGING REPAIR

Keep me posted about what you find or what you're told as I may be able to coment further and because what you learn will help other readers.

Bonus: If your boiler's an antique dating from the 1920s, check out this catalog from the National Boilers and Radiators - produced by the National Radiator Company

NATIONAL BOILERS & RADIATORS CATALOG [PDF] (1920)

by Phil - my boiler-made hot water is too hot

Thank you. I am waiting for HVAC man to call. My hot water was over 140 degrees and he adjusted it, or so he said. But I ran hot water from my faucet this morning, and put an oven thermometer in it and it registered 145 degrees.

I will let you know what he tells me. Thanks!

by (mod) - do you have a steam boiler?

A steam boiler, in its role heating a home, boils water to produce steam. So the temperature in the boiler will be closed 212 F. Or 100 C depending on how close you are to sea level.

If your steam boiler also uses a tankless coil to produce domestic hot water for washing and bathing, that water would be scalding hot unless you used a mixing valve to mix cold in with the outgoing hot to avoid scalding.

Watch out: That valve should be adjusted so that water at the tap is no higher than 120 degrees Fahrenheit. Otherwise people are going to get scalding Burns.

by Phil my hot water is now too hot - scalding

I have a hot water heater attached to my boiler; in the summertime, I have to keep the furnace running in order to have hot water. It's not a separate tank.

The water has always been set at 120. Then not long ago, I noticed it was scalding hot. Nothing had been touched.

The HVAC man came and did other adjustments confirmed the water temperature was over 140 and said he replaced/adjusted the mixing valve so the water was "about 125". Evidently his adjustment didn't work? I'm waiting to see what he is going to do now.

Can something happen just like that to make the water go from 120 to scalding hot?

by (mod) - control malfunction, hot water is dangerously hot - scalding burn risk

I think you are describing what we call an indirect fired water heater.

The water in the water heater is heated by a coil inside its tank. Hot water from your heating boiler circulates through that coil. Hot water from your heating boiler acts as a separate heating Zone

The domestic hot water temperature in an indirect water heater is controlled by an aquastat mounted on that heater that monitors heater temperature and, when needed, circulates hot water from the boiler through a heat exchanging coil inside the domestic hot water tank itself - thus reheating that water.

If the domestic hot water is too hot then if you have not changed any of the control settings I suspect the a temperature control on your water heater has failed - a bad aquastat or bad temperature sensor.

Those are explained at AQUASTAT CONTROLS - home

Another possibility is that a hot water tempering valve has failed at the water heater outlet.

Those are explained at ANTI-SCALD WATER TEMPERATURE CONTROL TYPES 

This conversation is a great example of the difficulty of trying to guess at what's wrong with a system and offering advice for its repair when we don't actually have a clear understanding of what kind of equipment is installed

Watch out: there is danger of someone being badly burned - either prevent anyone from running hot water, or safer, turn off the system completely as I fear that either a mixing valve or a temperature control has failed.

by Phil: temperature control at a No. 6 Everhot Tankless Water Heater

I appreciate your helping me. You know these old furnaces. No one I know has ever owned such an old antique boiler and they all are advising me to get rid of it before it "blows" up.

Plus it's very, very difficult to find an HVAC repair man. Younger ones just say to replace it. They have never seen one like mine.

So it's difficult for me.

You are the only people who can advise and have to deal with people like me who don't know what parts are called. Sorry.

My water heater is a #6 Everhot All Copper Tankless. Made by Everhot All Copper, Inc., Boston 16, MA. The "16" tells you it;s pretty old.

How long ago have we had zip codes like that? Attached to the water heater is a slim grey Honeywell device to adjust the temperature of the water.

Looks like it says LA0064 2017 but difficult to read.

Thanks for all your help before my 78 year old plumber calls me back.

by (mod) re: relationship of hot water heat, indirect water heaters, & heating boiler problems

Phil,

I've made good use of old cast-iron coal-fired boilers converted to gas or oil, properly fired and tuned and cleaned and running at about 79% efficiency - good enough to defer moving to a newer high-efficiency heating boiler in many cases.

Everhot tankless water heaters are still sold, as Everhot, now in Waterville MA, is a division of Therma-Flow, Tel: 1-800-654-8045 Email: sales@tfi-everhot.com Web: www.tfi-everhot.com
Therma-Flow, Inc.,191 Arlington Street, Watertown, MA 02472, MAIL: P.O. Box 416, Watertown, MA 02471-0416

Here is a link to current Everhot tankless water heater information: this will help you understand your hot water system.

EVERHOT TANKLESS WATER HEATER SPECIFICATIONS [PDF]

and here is the company's pertinent web page http://www.tfi-everhot.com/ExternalTankless_2008.html

Also see this article INDIRECT FIRED WATER HEATERS

Boiler Delivers Too Much Heat FAQs

Getting too much heat from my condo heating boiler

I live in a building that uses water boilers for heating.

There are 3 floors each with 5 suites per floor. It is extremely hot in my suite and I don't know how to cool it off other than opening the patio door which I can't do for very long being it's winter and very cold out.

Is there any other way to cool off the suite. I do not even have my thermostat on and it still registers 75 degrees Fahrenheit or 25 Celsius. >On 2016-12-16 y Anonymous

by (mod) re:

There should be shut-off valves at your heating convectors. If not, restricting air inflow at the convector or baseboard bottom will reduce heat output.

Also see our more detailed diagnosis and repair advice

Also see our diagnostics

at HEAT ANTICIPATOR ADJUSTMENT - fine tuning the room thermostat to prevent heat "overshoot" at the end of a heat-on cycle

at HEAT INSUFFICIENT or UNEVEN where our discussion of uneven heat also includes getting too much heat in some areas and possibly not enough in others.

at HEAT WON'T TURN OFF - if the boiler runs too long or never turns off

at THERMOSTAT CALIBRATION - to see if your thermostat is the cause of rooms getting too much heat, such as a thermostat mounted in a draft or on a cold wall 

Boiler Keeps Shutting Down FAQs

Oil fired boiler keeps going off every few days

My oil burner fires but runs just for a day or two then stops On 2016-12-20 by bob miller

by (mod)

Time to call a service tech, Bob. I don't think this is a problem a homeowner can repair.

From just the symptom I don't know if it's a loose wire, clogging filter, clogging nozzle, bad cad cell, or something else.

see OIL BURNER WONT RUN for common problems that could explain what you're seeing at your place.

Burnham XG2000 boiler goes off randomly

We have a Burnham boiler XB2000 heats then just goes out random power on but have to throw the switch to get heating. (Jan 21, 2015) Gina ward said:

Reply:

Gina

Your question sounds as if there may be a burner operating problem shutting down the system or a motor overheating and shutting off on thermal reset or a control problem.

Start by checking all wiring connections.

If you don't already have the manual for your boiler you can download a free PDF copy

at BURHNAM BOILERS AGE CONTACT MANUALS 

My boiler turns itself off - I have to restart it by turning up the heat

I have an older gas furnace that generates heat for water-based radiators.

The unit does not stay on consistently. It turns off and on at its own sporadically but never exceeds the set thermostat temperature and now has gotten to the point where the air in the room will be up to 12 degrees colder than the set temperature on the thermostat, especially when it is a cold night.

Oddly, it seems to turn off more often at night, then runs during the day. It "prefers" to be set at higher temperatures, as it is hard to stay on with a range between 65-74 degrees.

After the unit shuts off, I can turn the thermostat all the way off, then if I turn it up to 74 or higher it will click back on, as evidenced by a normal light humming sound.

I sometimes will turn the thermostat on and can hear it torque up downstairs, then several seconds later, no humming sound, the torque stops, and no heat is distributed.

If I keep repeating the process, after the torque and humming sound starts, then it may stay on typically for about 3 hours on a good day.

I always have to "restart" using the thermostat by 4 AM. I replaced the thermostat, and bled the radiators.

All radiators are on the same zone, and are running the same temperature to the touch. Unfortunately the unit tends to work precisely when the HVAC people come out, and they say that the problem can't be diagnosed unless the unit is totally non-operational. Please give me some ideas as to what this may be. On 2013-02-15 by Maria

by (mod) - maybe a bad temperature sensor probe

Maria,

Regarding " It turns off and on at its own sporadically but never exceeds the set thermostat temperature and now has gotten to the point where the air in the room will be up to 12 degrees colder than the set temperature on the thermostat, especially when it is a cold night"

I can't quite figure that out. You say the furnace never exceeds the thermostat temp - meaning it never overheats the room - which is proper operation.

Then you say air in the room is 12 deg colder than the thermostat.

When you see cold air in the room where are you measuring it? Check the thermometer right on the thermostat - that's the air that the thermostat is sensing.

Then I read comments about radiators - so we're not talking about a furnace (warm air heat) but rather about a boiler (hot water heat) or a steam boiler (steam radiators, steam heat).

In any event the thermostat diagnosis is a good place to start.

I would not keep cycling heat off and on. That humming may be a clue that a motor is having trouble starting. OR a safety sensor is shutting off your heating system. If so it sounds as if you're past due for a heating service call.

Perhaps if you stop messing with the controls, just leave the thermostat set at one place, and don't cycle the system on and off, you can keep a log of how the system acts that will help the service technician. Or if the system shuts down, leave it in that condition and call your heating company. That will make diagnosis a bit easier.

I will offer a GUESS that the temperature sensing probe that tells your boiler's primary control aquastat to turn its burner on or off may be failing OR the sensor may not be in good thermal contact in the sensor well - something that your heating service tech will proabably check out.

We describe that problem at AQUASTAT SENSOR PROBE HEAT CONDUCTING COMPOUND

Keep us posted. Daniel F.

Not Enough Heat from Boiler FAQs

Our heat isn't hot enough; room takes hours to warm up; we are using too much LP gas

Photo: Jimmy's Weil-McLain CG-11 Gas Boiler discussed here.

Our home is a late 60's pre-built with 1150 square feet. We have a Weil-McLain CG 11 hot water boiler, Taco sentry zone valve on the supply side, and I think the issue is with the zone valve.

We use 10% LP on a 500 gal. tank a week.

When the thermostat calls, the zone valve closes, the boiler fires, as does the circulator.

The baseboards get warm to the touch, but not 180 degree hot.

Once the heat set on our thermostat is reached, the boiler stops as does the circulator, and the zone valve opens.

We have our thermostat set at 65; it turns on the heat at around 63 degrees, and shuts heat off at around 66.

It takes close to an hour to raise our room 3 degrees.

Is using this much LP gas normal?

How has no damage occurred with the circulator running and the zone valve closed?

Thank you for your time. On 2019-12-19 by jimmy45

Reply by (mod) -

Jimmy:

I made slight edits to your question for clarity but I don't think I made any substantial change to what you wrote.

Your thermostsat operation

sounds normal: it turns heat on when room temperature drops a couple of degrees below the SET temperature and turn heat off when the room temperature is 1 degree above the SET temperature. That "overshoot" is common, and if necessary, could be reduced by

reviewing HEAT ANTICIPATOR OPERATION - if your thermostat even has that feature.  

Your boiler operating sequence

confuses me. It doesn't sound right to me that your zone valve CLOSES on a call for heat - that's backwards. If that's really happening that would certainly make getting heat into the room

You might want to ask your heating service tech to go over your boiler's operating sequence, or see my detailed step by step description at

BOILER OPERATING STEPS  - 39 Steps sequence in the operation of hydronic heating systems

The long time to get your room temperature up even 3 degrees

deserves some further investigation. The cause could be any of several problems such as a bad circulator pump, a partly-airbound system, a zone valve that doesn't fully open or improperly-set boiler controls.

Below at "Boiler runs but some or all rooms never get warm enough" I include more-detailed diagnosis and repair steps and links to more detail.

Your LP gas usage

I can't guess how much LP gas use is normal for your home because the amount of fuel needed and heat output needed to warm a home varies significantly by the home's rate of heat loss (how well a home is insulated, how much air leakage there is, how much glass there is, how much opening and closing of windows and doors occurs, etc).

But there are some sanity checks that one can make.

1. Look at the heating boiler's data tag

where you'll see the input BTUh consumption rate of your boiler. At GAS BTUH, CUBIC FEET & ENERGY https://inspectapedia.com/plumbing/Gas_BTUs_Volumes.php we give all of the ways to convert between cubic feet or other measures of LPG and btus. You can thus start by seeing the rate per hour (of "on" time) at which your boiler consumes fuel.

You'll need to watch or measure or count hours-on for your boiler.

2. Have your heating service tech be sure that the boiler is properly tuned and adjusted

. If your boiler's HI limit is set to 180degF that does NOT mean that the baseboard pipes will ever see that temperature; there is heat loss enroute; However your tech might agree to push up the HI to 190 or closer to 200F (not above that or the TPR valve will open); the thermal conductivity of baseboard is exponentially greater at higher temperatures so you'll see a bit more efficient heat transfer into the occupied space.

3. InspectApedia offers a number of articles on cutting heating cost

by finding where the waste or leaks are.

Two articles I like are

ENERGY SAVINGS PRIORITIES

and

HEATING COST SAVINGS METHODS

Boiler runs but some or all rooms never get warm enough

Gas boiler can't keep up with thermostat setting?

I have a Natural Gas hot water baseboard heating system in a split level 1350sqft house. My problem is the boiler is not keeping up the temperature set on the thermostats.

The Thermostat on the second floor will be set at 71 and the temp dropped to 66 before the boiler fired.

The first floor thermostat was set at 73 and the temp. Dropped to 72 there.

This occurred at the same time. The thermostats were calling for the boiler to fire the entire time because the zone valves were open the entire time.

I changed the electronic gas valve per the recommendation of the heating company that I had come troubleshoot my system last winter.

The water pump circulator runs the entire time while the thermostats are calling for heat as well. It seems to me that the circuit that tells the boiler to light or ignite isn't transmitting correctly. Thanks to anyone in advance for their expertise. (Dec 11, 2016) Wmig

Reply: Two different cases of "boiler not satisfying the thermostat"

You describe two different cases:

No problem: the first floor temperature drops to 72 F, one degree below the thermostast set temperature of 73F and the heat comes on - that's normal and not an issue. If we tried to flip heat on and off at just a fraction of a degree of temperature difference between room temperature and thermostat set temperature the heating system would oscillate or short cycle - inefficient and possibly leading to a failure.

Problem: First: where your seond floor thermostat is set to 71 and room temperature drops to 66 F before the boiler fires, the firing delay itself is not necessarily a problem nor abnormal.

That's becuase unless you're in a country (Canada?) where hot water heat is set up so that circulators run all the time, your thermostat simply turns on the zone circulator to send hot heating water to that zone.

Independently, the burner won't come on at your boiler until the temperature drops to the boiler's CUT-IN temperature. That's typically 15-20FD below the HI on the aquastat.

You may want to check your AQUASTAT HI LO DIFF SETTINGS - but when one zone works properly and the other, fed off of the same boiler, does not, then the problem is not at the aquastat.

But Second: if your circulator runs and the boiler eventually runs but the room temperature drops too far before recovering I suspect that the problem could be

• The thermostat itself isn't calling for heat until a big temperature drop occurs; I've seen this happen when the thermostat's internal parts were simply dust clogged
  
  In this case see
  
  THERMOSTAT CALIBRATION - to see if your thermostat is not responding properly to changes in room temperature
  
  - OR -
• The thermostat calls for heat but hot heating water is being delivered to the zone too slowly ( a circulator isn't running or a zone valve isn't fully open) or the water temperature is low because the flow rate is partly blocked, such as by a partly-airbound heating zone
  
  In these cases see these diagnostics, in this recommended order:

  HEAT ANTICIPATOR ADJUSTMENT - fine tuning the room thermostat to prevent heat "overshoot" at the end of a heat-on cycle

CIRCULATOR DIAGNOSTICS - if the too-cold zone has its own circulator, the circulator may not be running or may be damaged

ZONE VALVES, HEATING - home - if the too-cold zone has its own zone valve, the zone valve may not be opening fully

AIRBOUND HEAT SYSTEM REPAIR - partial air blockage means delivery of heat to a zone is impeded or reduced but not necessarily stopped completely

HEAT INSUFFICIENT or UNEVEN - more complete explanation of causes of uneven heat delivery in a building

HEAT WON'T TURN OFF - if the boiler runs too long or never turns off and can't ever satisfy a thermostat (I don't think this is your case)

In comparison: If the boiler temperature drops below the burner CUT-IN temp AND there is a call for heat AND the boiler doesn't turn on as it shouldfor ALL ZONES then

the AQUASTAT CONTROLS or its temperature sensor needs repair or replacement.

My House can't get warm enough unless thermostat set WAY up

I had new boiler put in a few years ago but it seems not to get house warm unless thermostat is turned way up, and then cost runs around 700 dollars and the baseboards never get super hot.

What could be the problem ? On 2018-11-09 by mark

Reply by (mod) -

Mark there are a lot of possible explanations - without more information from your installation I'm afraid my speculation is more arm-waving than helpful. I have no idea even what kind of heat you have: oil, gas, (presumably a hot water boiler), radiators, baseboards, convectors, multiple zone, one zone, zone valves, circulator pumps, etc.

In general there are a few very basic things that can be done like noting the temperature of the water in the boiler and noting that on a call for heat the circulator(s) run and zone valves open and heating pipes at the boiler get hot.

If all of that looks ok the problem could be air in the heating lines blocking or reducing hot water flow.

It's worth a call to your heating service company, asking for diagnostic help from an experienced technician.

Let me know what you're told and what further questions arise.

Boiler Runs, Makes Hot Water but We Lose Heat FAQs

Boiler makes hot water: Why does our Condo lose hot water in mornings and evenings?

We live in a condo association with water boilers for hot water that service several bldgs with 8 units in each bldg.

We are losing hot water in the morning and later in the evening but seem to have hot water during the day.

The boiler has been inspected and we are told it is working fine.

The problem was explained as the units have a single value in the showers that they are all faulty and causing a "crossover effect" where the cold water flows into the hot water and therefore no hot water. Is this a normal effect and how can it be fixed?

Late 1960-1970 Crane Sunnyday 102A Gas Boiler; cannot get the gas valve & circ. pump 2 run at same time- can make gas valve or pump work seperately. On 2016-12-14 by Jack L Coppock

(mod) Reasons your condo runs out of hot water

John,

Insufficient hot water capacity?

If your boiler is being used for both heating and to warm an indirect water heater, and considering that most people are using hot water for washing and bathing in mornings and evenings, it's no surprise if you run out simply because the water heater and its capacity are too small.

If this is your case, see INDIRECT-FIRED WATER HEATERS which use a separate heating boiler to produce a larger quantity of hot water

Often a building association will add hot water capacity using one of these approaches

• INSTANTANEOUS WATER HEATERS point of use systems that have little or no standby energy losses
• MULTIPLE WATER HEATERS IN PARALLEL to increase total hot water quantity
• MULTIPLE WATER HEATERS IN SERIES to stage hot water heating for varying levels of demand

Improper control settings?

But also, at the boiler the aquastat could be set improperly. Normally the boiler controls give priority to hot water for washing and bathing.

So the heating circulators won't run if the boiler temperature is too close to the aquastat LO setting.

We explain this at AQUASTAT HI LO DIFF SETTINGS

Boiler Runs but Won't Make Hot Water

Boiler won't heat our hot water

Hi. our problem is that while our central heating is fine, our oil boiler will not heat our hot water.

A local plumber has replaced all relevent parts, apparently, but still no hot water until the water has been running from the tap for around 25 minutes. - KennyBrown999@hotmail.co.uk - 9/9/2011

Reply:

Kenny: sorry I couldn't even guess at what's wrong with so little information. "all relevant parts" - may not have really been "ALL" since you still have the problem.

How is your hot water made - by tankless coil? If so the coil may be blocked with mineral deposits.

See the diagnosis and repair steps beginning

at  WATER HEATER PROBLEM DIAGNOSIS

Boiler Makes Hot Water, but Not Hot Enough FAQs

Hot water recirculating loop is not maintaining temperature in our indirect water heater

We're having a problem with a hot water recirculating loop from boiler to storage tank with tempering valve to building.

We're not able to maintain proper temperature in the indirect water heater tank. Any ideas? - Vivek 10.26/11

Reply:

Vivek,

If the hot water recirculating loop (I am guessing you mean domestic hot water for washing and bathing, not a building heating system) is not maintaining the required temperature I'd check in this order:

- is this a change in behavior or has it always been this way. If it's a new condition I'd look for a change in hot water use or a failure of a tempering valve (or someone messed with the valve) or a change in the water heater temperature settings

- if the problem has always been there, to the above I'd add a check for missing insulation on the water piping

Boiler or Furnace Door Gasket Replacement FAQs

Where to get a replacement fireproof seal for the cleanout door on my old Chevron oil furnace

I have an older Chevron furnace. There is a metal flap to the round "clean out door "that lifts up and there is a 3 by 3 inch seal/ gasket that resides on the underside of the flap door.

I believe it is made of asbestos. Looks like a CD . It's fire resistant. It fell off in pieces when I lifted the door .

I have no idea what it's called or where to get one. I have been to a few local supply stores with no luck. Can someone atleast tell me what it is? On 2015-11-18 by Laura

by (mod) - You need a wood stove rope gasket of the right diameter and length - widely available

It sounds like a fire-resistant gasket just as you suggest.

Avoid running a vacuum cleaner, clean up with damp wipes;

Check with your HVAC supplier or if no success there check with a woodstove supplier for a replacement gasket that is not asbestos.

I've used water glass and non-asbestos gaskets to replace these with good success for many years.

Gasket material is sold as ropes of different diameters and in lengths by the foot. You simply need

- the approximate diameter of the door gasket rope

- the approximate length of rope gasket needed

Then go to any heating supplier or woodstove suppler or coal stove supplier or online vendor and search for any of the following terms

• Woodstove gasket rope
• Woodstove door gasket
• Woodstove rope gasket
• Fireplace door gasket