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Photograph of a modern oil-fired heating boiler Heating System Troubleshooting FAQs-4
Older Q&A on heating system repairs

Heating system installation, repair, maintenance questions & answers set #2:

More frequently-asked questions & replies on how to troubleshoot & repair heating systems in buildings.

These heating system articles answer questions about all types of building heating systems and describe how to inspect, diagnose, and repair heating system problems, how to cut heating bills, and heating system safety, heating system efficiency and heating trouble-shooting advice.

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Heating System Q&A Set #4

Smith cast iron boiler data tag information (C) Daniel FriedmanThese questions & answers about troubleshooting heating systems in buildings were posted originally at HEATING SYSTEMS - home - that's a place to start diagnostics for your heating system.

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Photo: example data tag for a boiler. More examples of data tags and notes on finding them are

at DATA TAG IDENTIFICATION & LOCATION

On 2018-01-21 by (mod) - where to start checking

Anon

At the top of this article you'll see LIVE LINKS for where to start checking

NO HEAT - BOILER - if your heat is made by hot water such as by radiators or baseboards

NO HEAT - FURNACE - if your heat is made by forced hot air

On 2018-01-21 1 by Anonymous

My problem is i turn thermostat up nd the furnace dont kick on what is the problem

On 2018-01-17 by (mod) -

re-posting

Charles Brown said:
I would like to mention briefly what all you need to inspect in a heating or HVAC system. You should inspect the electrical components, internal components, cooling components, and the conditioning unit. This will ensure that your heating system runs smoothly.

On 2018-01-16 by (mod) -

Sorry, Ralph, I can't say. Probably you posted on a different article at this site. Check your browser's history.

On 2018-01-16 by Ralph Linck.

I already wrote , where is my pastbwuestion please?

On 2018-01-12 by (mod) -

Agreed

On 2018-01-12 by Eric

Thank you all for the input, I am already installed on the cold water line so I will just stay put and not worry about moving to hot water to gain higher humidity levels.

On 2018-01-11 by (mod) - DO NOT try feeding hot water from your water heater's drain valve.

Adding:

DO NOT try feeding hot water from your water heater's drain valve.

You will have chosen the worst place to feed hot water into a humidifier as you'll be draining sludge and scale from the bottom of the water heater.

On 2018-01-11 by (mod) - using a T- valve on hot water supply?

Eric

I do not think a T-valve would be the proper application for providing hot water to your system humidifier.

Typical T-valves such as the Mondeo T-valve I illustrate below, are ball-valves used to divert flow from a primary input source to one of two different destinations. The ball of the valve is drilled straight through and then an intersecting drill opening is made at a 90 degree angle to the first passage.

Ball valves are intended to be used in the fully-open or fully closed position, though some suppliers describe using a T-valve to permit sending output to two destinations simultaneously - you'd see reduced flow rate to both of them compared with a straight ball valve or an L-valve.

Also there could be a risk of pressure-loss and backflow of unsanitary water from the humidifier to the building water heater or plumbing system (though double check valves could mitigate that risk).

The simplest installation uses a saddle valve that punctures a hot water line (or in my OPINION better, a cold water line) and uses a small diameter flexible copper tube to conduct water to the humidifier. However many plumbing codes no longer permit these valves.

Instead, in my OPINON, it would make more sense to simply install a tee in the hot water supply piping (or in my OPINION better to cold water piping) and then connect a simple ball-valve or gate valve (to permit flow adjustment) in line with the outlet of the tee that will feed the humidifier.

Unless you are going to keep filling your humidifier manually, and unless your humidifier includes a water feed control in its design, you'd want a sanitary float control valve to admit water into the humidifier.

BOTTOM LINE: I would drop the whole idea of connecting hot water to the humidifier.

Why?

There might be a small improvement in the production of moisture being sent into your furnace supply plenum or supply air duct by using hot water, but that benefit is likely to be offset by the formation of mineral scale and crud that HVAC technicians find troublesome as scale fouls controls and moving parts and increases service cost.

OPINION: frankly I am not a fan of central humidifiers that feed water into a supply plenum over a furnace heat exchanger. In over 40 years of building inspections I have seen that most of the central humidifiers I've seen installed were not maintained, were not working, and many of them had leaked into and caused costly, even dangerous damage to the furnace heat exchanger.

For those reasons I prefer point-of-use portable humidifiers such as in sleeping areas.

See CENTRAL HUMIDIFIER LEAKS into DUCTWORK inspectapedia.com/aircond/Ductwork_Ice.php#Humid

and

See HUMIDIFIERS & HUMIDITY TARGET inspectapedia.com/sickhouse/Humidity_Level_Target.php

On 2018-01-11 by Eric

@Eric,
Correction: I meant to ask if I can screw a T-Valve onto my water heater drain valve on the bottom, not onto the water shutoff valve.

I've added a humidifier to my furnace and would like to use hot water (recommended by manufacturer) from my hot water heater to supply water to the humidifier.

Can I screw a T-Valve into my water shutoff valve, add a new shutoff on the other end of the T-Vavle, and use this to supply my humidifier without violating codes?

On 2018-01-06 by (mod) -

Eric

Check that at the thermostat the FAN switch is set to AUTO, not "ON"
then

Check the diagnostic steps at

FAN WONT STOP - LIMIT SWITCH - inspectapedia.com/heat/Furnace_Fan_Wont_Stop.php

Also see

FURNACE BLOWS COLD AIR inspectapedia.com/heat/Furnace_Fan_Blows_Cold.php

On 2018-01-06 by Eric Harmon

Fan on furnace continuously runs and blows cold air after heat stops

On 2018-01-02 by (mod) -

Marsha

Try starting at

https://inspectapedia.com/heat/Heating-Boiler-Diagnosis.php

On 2018-01-02 by Marsha

@Marsha, just to narrow down some things we have changed the batteries in the thermostat and even reset the thermostat. Still no change.

Hello. I have a water pump unit and we seem to be having issues with it heating. The thermostat is on 72 but the temp reading is at 65. It is very cold here 16 to be exact. I was wondering if I should be calling a repairman to come and check it out.

On 2018-01-0 by (mod) - electric furnace will not heat above 64 degrees.

I would be sure that you don't have a dirty air filter in your furnace, and then

I would feel to see that you have air being delivered at each supply registers, and that thete is warm air being delivered at each Supply register.

if some registers are not delivering air then you need to look for disconnected or blocked air ducts

If you have warm air delivered at each Supply register then it's time to start looking for drafts or significant areas of heat loss in your building.

On 2018-01-01 by marilynsayrehogsett

My electric furnace will not heat above 64 degrees. Any ideas?

On 2018-01-01 by (mod) - marginal heat discovered during very cold weather

Agnes,

During cold weather the condition that you described might be normal for a heating system that is a bit marginal.

I would check the following things

First check that all of your heaters are working

Then check to be sure that any storm windows provided on your building are in the down or closed position

Then feel with your hands for drafts around windows and doors. Improving Window and Door weatherstripping can stop a draft.

Air leaks are the first thing to attend when trying to make a building warmer.

On 2018-01-01 by Agnes

I have electrical heat. The temperature outside is below 0 degrees. I set my temperature inside my house is 67 degrees but it only reach 66 degrees and the heater does not stop blowing. Is that normal?

On 2017-12-28 by Eric B

My Utica boiler was burning gas, but my system wasn't circulating the water (it serves the second story of my home).

I changed the Grundfos circulation pump, and it appears to be working, but heat isn't getting through my baseboard pipes.

I'm trying to bleed air from the system, but there are no bleeder valves along the baseboard radiators, just the one atop the expansion tank near the boiler. I opened that valve, and immediately got water coming out.

1.) How do I determine if air is in the piping, and force it to the expansion tank bleeder valve?

2. Although I meticulously checked for a bleeder valve along the 2nd floor piping, should there be one at the highest elevation in the system that I've missed?

Should I install one on the 2nd floor?

On 2017-12-17 by (mod) - The 2 red wires are the zone valve end switch wires.

RIght Gene
The 2 red wires are the zone valve end switch wires.

One red wire connects to the R-side of the transformer (Think "R" = "Red" and look for a little "R" that may be stamped on low voltage transformer by its wire connector screws)

The other red wire connects to one side of the external DPDT circulator relay that operates the circulator pump. (DPDT = "double pole, double throw" switch)
It's that relay that actually is going to send 120V to run the circulator pump

On 2017-12-17 by Gene12/16.17

Ok I was going to try it again I am at the end switch there are 2 wires one goes to the relay to turn on the circulator pump which one and do what with the other wire ? Ground to the yellow from the transformer . I think it will work Hope so.

On 2017-12-16 by (mod) - Typical zone valve yellow & red wire connections:

Yellow wire connections at the zone valve: the pair of yellow wires on a zone valve are the zone valve motor actuator control.

One yellow wire connects to the C terminal on the low voltage transformer.

The second yellow wire connects to a "heat on" wire from the room thermostat.

How does this little zone valvce yellow wire circuit work?

On a traditional two-wire room thermosatat one wire, usually the red one, connects to the R terminal (24VAC live) on the low voltage transformer. The second thermostat wire, usually white, connects to the yellow zone valve motor actuator wire.

The second yellow zone valve wire normally connects to the C terminal (Common) on the low voltage transformer.

When the thermostat calls for heat it's acting as a low-voltage (24VAC) "on" switch that takes voltage from the low voltage transformer, through the thermostat, to the zone valve actuator motor. The second wire from the zone valve back to the low voltage transformer completes the circvuit.

Red wire connections at the zone valve: the pair of red wires are "end switch" wires used to energise an external relay that turns on the circulator.

One red wire connects to the R-side of the transformer (Think "R" = "Red")

The other red wire connects to one side of the external DPDT relay that operates the circulator pump. (DPDT = "double pole, double throw" switch)

At the thermostat

The red wire from the heater or air conditioner control is mounted to the "R" terminal on the backing plate. Typically the red wire is originating at the heating or air conditioning low voltage transformer and brings power to the thermostat..

The white wire from the heater or air conditioner control is mounted to the "W" terminal on the thermostat mounting plate. Typically the white wire is taking power from the thermostat to the operating control circuit board in the heater or air conditioner.

On 2017-12-16 by Gene12/16.17

Well I This is how I have it here I got a whole roll 6 inch diameter of 4 wire sheath covered 1 red,1 white, 1 blue 1 yellow it is right size all for $ 2 . So I am at the zone valve vertical screws on top TH+TR yellow+white wires.. Then TH in the middle gets the Red wire from thermostat then Blue wire on TR transformer wire...

Then the End Switch wire I have a Red and a White wire then I take the red wire to the relay and the white wire to the ground . Do you see any reason why this would not work ? Is there a hot wire as well as a ground wire on end switch ?

On 2017-12-15 by (mod) -

No Gene not so.

Take a look at a typical Honeywell zone valve. There are two identical red wires and 2 identical yellow wires. Those are not polarized.
Search InspectApedia.com for ZONE VALVE WIRING https://inspectapedia.com/heat/Zone_Valve_Wiring.php to see details.

For the low voltage 24VAC transformer by convention

A "C" or common terminal wire on the low voltage transformer is connected to the control relay that operates the heater or air conditioner, and

an "R" terminal on the transformer is connected first to the thermostat (which acts as an "on-off" switch) and from the thermostat onwards to a thermostat terminal found on the heater or air conditioner's primary control or circuit board.

Details about thermostat wiring and low voltage control wiring are found
at THERMOSTAT WIRE CONNECTIONS https://inspectapedia.com/heat/Thermostat_Wiring_Instructions.php

On 2017-12-12 by Anonymous

First you say it does make a difference on the polarity how can I make sure it is right ? I got a blue and yellow wire out of the transformer I got it as blue hot and yellow as ground or neutral . I have trouble making out the hand drawn article. I did get to put out some heat with the zone valve manually opened if this is possible . Why can I not get with the zone valve ?
inspectapedia.com/heat/Honeywell_Zone_Valve_Wires_2.jpg

On 2017-12-12 by Gene 12/11/17

Well I got tired of using those ventless heaters and trying to get this to run with zone valves and propped the zone open and connected the thermostat to relay and it is running good for now . Maybe I can try it another day tired of messing with it.

Some tell me that I should know the 24 volt transformer polarity and forget which I should use then someone says it does not matter which when you got AC going into the transformer you get ac current come out .How to check the current from what I have ?

How to connect wire for room thermostat and water pump prop open the zone valve and run just the pump

On 2017-12-11 by (mod) -

Gene

I may be missing something too, but at https://inspectapedia.com/heat/Zone_Valve_Wiring.php (ZONE VALVE WIRING) where we note that on a typical Honeywell zone valve there are 4 wires, 2 red and 2 yellow, follow the instructions given by Honeywell and repeated at

HONEYWELL ZONE VALVE INSTRUCTIONS https://inspectapedia.com/heat/Zone_Valve_Wiring.php#Honeywell

this old sketch from heating school shows how we wired those connections

https://inspectapedia.com/heat/Honeywell_Zone_Valve_Wires_2.jpg

On 2017-12-11 by Gene 12/11/17

@Gene 12/11/17, before I had tried to put the ground wire for the transformer with the ground wire for 110 volt ground that did not very well. But now that I have different for each .

I must be missing something here I have the wires from the thermostat to TH+TR and TH and TR zone valve which has 2 wires on for END Switch on zone valve .

Now The transformer has 24 volt blue wire to go to the to top of relay and the yellow wire from the transformer to a ground connection . I have the the wire from the end switch on zone valve to lower 24 volt side and the other end switch wire also to the ground .The other side of relay has 110 volts at top and pump wire at the lower side .

On 2017-12-10 by Kip

danjoefriedman: Thank you for your input, however, there is only one ID type tag inside the furnace door on the front of the furnace. I took a picture but do not know how to attach it on this post.

This is the information on the tag: "C.A. Olsen Mfg. Co, Elyria, Ohio", "Approved as forced air furnace", "For Nat gas", "Input BTU/Hour 150000","Bonnet Capacity BTU/Hour 120000", "Model 1-150", "Series - 4" No other ID tags only instructional tags of how to oil, relight pilot light, etc. I guess I am just SOL trying to determine the age. Thank you though.

On 2017-12-10 by Matthew D

Our Raythem boiler seems to be cycling on and off every few seconds: sometimes at 3 to 5 or ten second intervals. This does not seem right to me: and ideas what might be the problem?



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