FAQs on how heating boilers work & on the steps in its operating sequence?

This article series describes how a hot water heating system (hydronic heat) actually works, step by step, to heat a building.

Q&A on Heating Boiler Sequence of Operation

Training in proper operation sequence of heating system equipment and in the function of its controls is a step towards technical correctness. If you do not understand how a mechanical system works you cannot reliably expect to observe missing or defective components.

On 2019-01-31 by (mod) - what to do if you have no heat

See the NO HEAT diagnosis and repair steps starting at NO HEAT - BOILER https://inspectapedia.com/heat/Heating-Boiler-Diagnosis.php

On 2019-01-31 by J

I have oil heat and hot water have oil in tank
Have hot water
No heat

On 2018-03-10 by Katty

Very informative

On 2017-12-17 by (mod) - not enough domestic hot water for washing & bathing

Mike,

I've let us mix up different systems.

Air in the closed-system of heating boiler pipes, radiators, baseboaards, can prevent or slow the movement of heating water out of the boiler and around the space heating loop.

That would have nothing to do with a weak hot water flow at a faucet or tub.

Weak hot water flow is discussed at an article here HOT WATER PRESSURE IMPROVEMENT -https://inspectapedia.com/plumbing/Hot_Water_Pressure_Improvement.php

On 2017-12-12 by mike

thank you so far. so air in the system will make the hot water slow to a trickle out the faucet at the tub all when you turn the hot water on it bangs. so bleeding the air out will fix this problem? thank you 4 your help

On 2017-12-11 by (mod) - fixing an air bound heating system

Mike,

The air-bound problem is often pretty easy to fix, either by strategic opening of air bleeder valves on upper piping loops or by forcing air out using a pony pump.

Start with the diagnosis and repair steps here AIR-BOUND HEATING SYSTEMS https://inspectapedia.com/heat/Air_Bound_Heating_System.php

On 2017-12-11 by mike

Hi I changed the circulator pump out on the hydronic boiler an have air in the system im guessing cause the hot water pressure has slowly becoming less an less to the point that I hardly have any hot water pressure throughout the house, How do I fix this I am LOST. Please some one help thank you

On 2017-11-01 by go

oil fired furnace. one radiator is not circulating hot water. Bled the rad, some air came out but never got hot water coming out.

Did the same to the other rads that are working, but again no water comes out the bleeder valve as would always happen in the past. Why is this one rad not circulating hot water, why does water not come out of any rad once the air has escaped out of bleeder valve?

On 2017-02-03 13:22:53.139529 by Joe

Looking at your diagram of the hot water boiler system it looks to me like my expansion tank is located on the return line.

That is, the hot water returning from the zones goes through the expansion tank, then into the pump, then into the boiler then out again. Is that even possible?

Should the expansion tank be on the other side of the boiler? Would my boiler even work if I am reading this diagram correctly? (It has not been very efficient in the 10 years we have lived here)

On 2016-11-22 15:34:20.274087 by Anonymous

The water boiler is not staying 0n to heat all the lines

On 2016-11-19 22:52:22.760424 by (mod) -

George,

If you search InspectApedia.com for STEAM BOILER OPERATION you'll find a lengthy series of detailed articles about steam heat inspection, repair, design, components etc.

Good luck with your test.

On 2016-11-19 13:26:06.683355 by george

describe any one system of producing steeam from water using boilers

On 2016-02-23 19:49:30.437198 by (mod) -

Rudy I can't diagnose this excellent question from a brief e-text. But what you describe sounds abnormal and possibly unsafe. We don't know if there is a thermostat wire short, a bad control board, a bad thermostat, or a loose connection or what. I'd suggest asking for help from a trained service tech, on site.

On 2016-02-23 18:38:32.918115 by Rudy

I have a gas burner but it seems like it won't stop working, I set the thermostat to 55 F and the room temp is 70 F why the burner is still working every 10 5-10 mins?

Thanks

On 2016-02-15 14:55:19.452635 by (mod) -

Tony,

If your boiler is a hydronic unit - that is it makes hot water that circulates through baseboards or radiators - it would not normally consume water

. In that circumstance my opinion is that as long as you keep an eye on the system to be sure that it is not leaking (watch for a drop in boiler pressure when the boiler is off or cold) it can be used safely for the few hours needed to replace the water main.

You might shut off the supply valve to the boiler during the repair to make double sure that it doesn't back-drain out the open water pipe. (It shouldn't anyway as there should be a check valve but the check valve could be leaky). DO NOT FORGET to turn the water supply back on to the boiler when the repair is complete. \

If you see boiler pressure dropping below 12 psi when the boiler is cold or if you hear gurgling in the baseboard pipes or if you see steam discharge at the boiler or its TP valve, turn the system off.

On 2016-02-15 14:17:49.858462 by tony

I have a leak in my main water line, when I repair it can the boiler still be use or will it get damaged

On 2016-02-14 16:57:49.775540 by (mod) -

Ellie if you are hearing gurgling sounds in the baseboards there is air in the system that needs to be purged. Assuming this is hot water heat, not steam heat, you should not be hearing sounds from the pipes. The risk is that ultimately the baseboards become air-bound and you have no heat at all. Search InspectApedia for AIR BOUND HEATING BASEBOARDS to read details.

On 2016-02-14 14:41:18.782773 by Ellie

I have a oil boiler with baseboard units in each room. Should I be hearing the water rush in or does that mean the water is low?

On 2016-02-01 20:42:32.513325 by Charlie

I have no shut-off valves on my baseboard hot water heating system. If I have a break or leak I would need to shut my water source to my home to do the repair. I would like to install a shut-off valve in the heating system. Should I install it in the line going to the baseboards or return line at the furnace?

Question: what component turns on the burner?

(Feb 23, 2014) Tom said:
In your sequence I didn't see what component turns on the burner. And isn't there a gizmatron that proves draft before the burners ignite?

Reply:

Tom: what turns on the burner depends on the heating system type, and in some cases wiring styles between countries;

In the U.S. an oil fired boiler is turned on and off by the aquastat control.

The thermostat starts the circulator; as water temperature returning to the boiler drops it to the cut in temperature the aquastat turns on the boiler.

For a warm air furnace the thermostat turns on the burner, the plenum heats up, and the fan limit turns on the blower.

Question:

Jan 8, 2015) Anonymous said:
I have baseboard hot water heat. There are 3 zones. When any of the zones kick in you can hear water running through the system. Is this normal or is there a problem?

[answered elsewhere for same poster]

Question: I need to flush the coil

(Feb 18, 2015) Mike said:
i have an old boiler made by axeman-Anderson I need to flush the coil and I do not know how I have everything that you need but I do not know what to do if I can find the in and the out I can connect the hoses to them and begin flushing I am a disabled veterans and times are rough trying to save some money like I said I have two hoses the asid and the pump

Reply:

Sure, Mike. Glad to help.m

See the tankless coil Cleaning description at

inspectapedia.com/plumbing/Tankless_Coil_Clogging.htm

Question:

(May 25, 2015) larry said:
no hot water coming from oil fired burner and seems to be air in the system

Reply:

Larry the diagnostics at AIR-BOUND HEATING SYSTEMS - home - have what you need for this problem.

Question:

26 Oct 2015 Mary said:
Furnaace comes on every hr. for ax. 4 minutes even though the thermostat is set at10 deg. C and room temp. is 20 degrees C.

Reply:

Mary, see the diagnostics beginning at BLOWER FAN OPERATION & TESTING and also see

• FURNACE FAN CYCLES AFTER HEAT
• FURNACE FAN CYCLES DURING HEAT
• FURNACE FAN STOPS EARLY

One of these is probably the problem you're seeing.

...

Continue reading at BOILER OPERATING STEPS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

No heat? see HEATING LOSS DIAGNOSIS-BOILERS

NO HEAT - BOILER

OIL BURNER WONT RUN

BOILERS, HEATING - home

BOILER OPERATING PROBLEMS

BOILER CONTROLS & SWITCHES

DIAGNOSE & FIX HEATING PROBLEMS-BOILER

GAS BURNER FLAME & NOISE DEFECTS

HEAT WON'T TURN ON or if needed, HEAT WON'T TURN OFF

RADIATORS for ROOM HEAT - topic home, for cold radiator or baseboard diagnosis and repair

Suggested citation for this web page

BOILER OPERATING STEPS 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

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