Common Problems with Boiler Stoves and How to Solve Them

Common Problems with Boiler Stoves and How to Solve Them

Following our article on problems with wood-burning stoves, we’re now turning our attention to boiler stoves.

These are all problems that occasionally crop-up with boiler stoves. Where possible we’ll tell you how to solve them yourself. If we can’t do that, hopefully we’ll at least point you in the direction of possible causes.

So, here are some issues that might result in your boiler stove not working correctly.

Boiler not heating radiators downstairs

This usually points to a problem with the circulating pump on the heating system. Radiators upstairs can heat on gravity but downstairs radiators require a circulating pump.

Stove is going out with unburnt fuel left

Try increasing the setting on the boiler thermostat. If the problem persists it could be a faulty thermostat in need of replacement.

Also, check that a heat leak radiator (i.e. a radiator that is on all the time when the boiler stove is working) has been fitted if the appliance installation instructions say that one is needed.

If you do have a heat leak radiator, check that it is working properly. It should be fitted with two lockshield valves, which cannot be turned off.

Check the gravity circulation to your hot water tank is working properly. Boiler stoves rely on the heat leak radiator and the hot water gravity circuit to give them work to do. If these are not working and there is not enough work for the appliance, it will be shut down by the thermostat and the fire will go out.

Stove going out overnight with all fuel burnt

This could be due to the boiler thermostat being set too high. As a result, fuel topped up for an overnight burn has been spent too quickly because the stove has been producing more heat than necessary.

You just need to turn down the boiler thermostat and find a balance between burning all the fuel and the stove going out.

Boiler stoves burn more fuel when the circulating pump is on for the heating. In most circumstances, you can switch the pump off at night and set it to come on automatically using the time clock. This will extend the burn time and stop the fire going out early in the morning.

Stove is not shutting down properly

Check that all the door and glass seals are sealing properly. Also, ensure that the flap on the boiler thermostat closes properly and is not obstructed by debris, such as coal or ash.

If the water temperature of the stove is very hot and the boiler thermostat is free from debris but will not close it may need adjusted by your installer. Also there could be a fault with the thermostat. In this case the thermostat may need to be replaced.

If the water in the boiler is not hot then the thermostat will automatically be kept open while the boiler stove increases the water temperature.

Switching on the circulating pump will send cold water back from the radiators. The thermostat will react to the drop in temperature by opening the air intake flap and the stove will fire up. This is normal.

Stove not getting radiators up to temperature

Try increasing the temperature setting on the boiler thermostat. If this doesn’t work, check that the air intake flap is opening properly when the thermostat temperature is increased.

When the stove is burning well but the radiator temperature is not at the desired level, it can be because too many radiators are connected to the boiler stove. You can check this by turning off half of the radiators and seeing if the temperature increases.

If the radiators still fail to reach temperature then you could have a problem with your circulating pump. Check whether the radiators are warm at the top and cold at the bottom. This indicates circulation problems.

If the radiators do come up to temperature after turning half of them off, turn one radiator on at a time to see how many you can use before it impacts the temperature. A boiler stove with an insufficient heat output is likely to be the cause of the problem.

Water appearing in the stove

This can happen when warm, damp air in the appliance hits the cold surface of the boiler during lighting. This type of dampness should disappear shortly after lighting when the boiler reaches temperature.

If the dampness continues it might be because a pipe thermostat is either not working properly or is set too low. It should be set to allow the pump to operate above approximately 40°C.

Another possible cause is condensation from the flue. This can happen if a stove is not working hard enough. Flue gases can cool when leaving the stove and create condensation, which goes back into the stove. Turn up the boiler thermostat and avoid heating radiators when the stove is idle to resolve this.

If the problem persists, check that the heat leak radiator and gravity circulation to the hot water cylinder are working properly. If the stove does not have enough work to do it will be shut down by the thermostat and this can cause condensation to build up in the stove and the flue.

Condensation problems inside the boiler can be caused when a boiler with an output higher than that required for the heating system has been specified in error. This leads to the boiler spending to much time at a slow burning rate and this can cause condensation problems inside the boiler or flue.

If there is dampness when the fire is out and it isn’t coming from the flue or chimney, a leaking boiler in the stove could be the cause. Have this checked by an engineer.

Radiator is warm at the bottom but cold at the top

This is usually due to a build-up of air in the radiator. Use a radiator key to loosen the square plug vent at the top of the radiator and release the air.

Radiator is warm at the top and cold at the bottom

Circulation problems are the likely cause. Check the radiator valve is open fully and if this doesn’t solve it, check that the lockshield valve at the opposite end is also fully open.

The system may need balancing if all the radiators are heating but one or two are warm at the top and cold at the bottom.

Radiators closer to the circulating pump will get priority over those further away on long runs or smaller pipe work. Your heating engineer can balance the system by partially closing the lockshield valves on the radiators that are working well. This will give a bigger priority to those further away.

If you’ve got a problem that wasn’t answered in this article, please get in touch and we’ll try to write an article to help you.


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Showing 1 to 20 comment(s) of 149

Gr8Fires 2020-01-21 12:46:50
@ Oana Oana Hi Oana, It sounds like something's amiss with the system. Probably best to get your
installer back out to take a look. Thanks, Gr8Fires

Oana Oana 2019-12-24 10:21:52
Hi I have a 21kw back boiler stove installed 2 years ago, we did really used the stove as it
doesn't heat all the roads properly, some of them are really cold, so we use the central heating
most of the time. Last night I had the central heating on all night, and this morning the stove was
very hot ,( hoter than some radiators in the house) d the pump on, eventho we did not light the fire
for a month . I turned off the central heating and after 5-10 the pump went off too.... what can be
wrong with this? Why is the central heating, heating my stove? Thank you

Gr8Fires 2019-12-16 13:46:36
@ Calvin Chaplin Hi Calvin It can be tricky to get the system working correctly. We'd suggest
getting your installer out to make sure everything is as it should be. It's easy to make things
worse if you try to DIY. Thanks, Gr8Fires

calvin chaplin 2019-12-14 10:01:42
hello i have just installed a 30kw boiler stove to heat 8 double radiators and hot water but the
problem i,m having is the stove is getting scalding hot whilst the radiators are only look warm (at
the top) and hot water is being forced out of the system. ..the circulating pump is approx 45 feet
of 22mm pipe away from the stove so would a second pump next to the stove cure the problem or just
move the existing one closer?. many thanks. calvin.

Gr8Fires 2019-12-06 12:34:10
@ Natasha Harrigan Hi Natasha Did you check that the boiler stove has enough heat output to heat
all the radiators and provide the warmth you need for the room? Here's some advice on burning
overnight: Thanks, Gr8

Gr8Fires 2019-12-06 12:13:50
@ Annmarie Kelly Hi Annmarie Sorry, that sounds like something someone would have to investigate in
the property. It's not an issue we've come across. Thanks, Gr8Fires

Natasha Harrigan 2019-12-05 13:49:13
Hi there ever since installing my back boiler stove we have had problems with it not making the room
hot like it should and it barely heats the roads we also have a lot of wood/ coal sunburnt in the
morning can you advise please? Kind regards natasha

Annmarie Kelly 2019-12-02 07:29:36
Hi, Problem we have is , since we got WiFi heating controls connected for oil heating, out back
boiler in stove is not heating any of our rads. It heated the rads before we got this in. What is
causing this problem.

Gr8Fires 2019-11-25 15:00:12
@ Sandra Bergin Hi Sandra Did the boiler stove you bought definitely have the same 'oomph' as the
old range? It could be that the heat output is not great enough to heat everything you need. We'd
recommend getting your installer back out to check this and to advise on the
thermostat. Thanks, Gr8Fires

Sandra Bergin 2019-11-17 19:03:04
Hi .I took out my range with bavk boiler and got a back boiler stove in and with the range I never
had to touch the thermostat it was always at 40 and heated radiators and if I have it at
40 or more it heats the water but only half the radiators. If I turn it down it will heat the rads
at 20 degrees but only luke warm.i have moved the thermostat several times cause that's what I was
told to do but still messing with me please.where should the thermostat be.

Gr8Fires 2019-11-11 12:26:08
@ Sue Hi Sue Please find some possible reasons in this article:
Thanks, Gr8Fires

Sue 2019-11-06 15:23:18
Why does my multi fuel stove smoke when I open doors ? The smoke and smell is herrendous I have to
open windows to get smoke and smell out it gets into the back of my throat !!

Gr8Fires 2019-10-21 09:31:18
@ Michelle White Hi Michelle It's hard to offer more specific advice than what we've said in the
article above. If you've investigated those things without success, we would suggest getting a
competent heating professional out to take a look and try to diagnose the problem for you. Many
thanks, Gr8Fires

Gr8Fires 2019-10-21 09:29:08
@ Karen Roach Hi Karen There are a few possibilities, but we'd recommend getting a competent
heating engineer to take a look because it's so easy to make matters worse when trying to fix a
boiler stove system. Thanks, Gr8Fires

Gr8Fires 2019-10-21 09:23:25
@ James Hoey Hi James Difficult to suggest anything other than the information in the article above
without knowing the specifics of the installation. If you're unable to diagnose the issue having
investigated the things above, we'd recommend getting a competent heating engineer out to take a
look. Thanks, Gr8Fires

Gr8Fires 2019-10-21 09:20:34
@ Claire Falls Hi Claire It's best to have a professional come and take a look. Condensation could
be a sign of a leak, or it could just be a ventilation issue in your home. The noise might be
kettling, which can be due to operating the stove at too high a temperature or due to a limescale
build-up. Thanks, Gr8Fires

Gr8Fires 2019-10-21 09:17:55
@ Scott O'Hara Hi Scott We'd recommend getting a professional out to take a look for you. There are
too many possibilities and it's hard to know without seeing the specifics of the
installation. Thanks, Gr8Fires

Michelle White 2019-10-21 05:55:04
Hiya we have a chiltern freestanding parkray. We left it go out through the summer just lit it back
up for the winter never had no problem before it's Gravity fed .water boiling hot but all or
radiators stone cold .they've been bled , pump is working any help will be gladly received.

Karen Roach 2019-10-19 15:40:51
We have gravity fed wood burner and radiators hot but water cold coming out of boiler can you help

Karen Roach 2019-10-19 15:40:51
We have gravity fed wood burner and radiators hot but water cold coming out of boiler can you help

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