cancel
Showing results for 
Search instead for 
Did you mean: 

More Central Heating Woes

Highlighted
Anonymous
Not applicable

More Central Heating Woes

Back in 2015 I had some issue with my heating system and I was going to replace the boiler but the issue was fixed using an expansion chamber, but now it’s playing up again.

The control radiator in the hall is hot, and when I say hot I mean 62.3° according to my digital pointy thermometer, and is making screaming noises. The thermostat in the same hall (a window away from the control radiator) says it is 24° with the On/Off temp set at 22°, having turned it down in desperation to cool the place down.

So why is the control radiator on? Yesterday the lounge room was over 26° and considering this is a double height room that’s cosy.

Any thoughts on this?

37 REPLIES 37
Highlighted
Superuser
Superuser
Posts: 3,245
Thanks: 949
Fixes: 8
Registered: ‎06-04-2007

Re: More Central Heating Woes

I'm no expert, but can you tell if your thermostat is on?  ie is it the thermostat not working, or is the thermostat switching the boiler off, but the boiler not actually turning off?  The might narrow it down a little.  If its the thermostat then that should be fairly cheap and easy to change.

Highlighted
Aspiring Hero
Posts: 2,847
Thanks: 847
Fixes: 82
Registered: ‎21-09-2009

Re: More Central Heating Woes

I had an issue where the motorised control valve for the heating pump wouldn't close and it kept pumping water round the system and firing the boiler all the time. House was like a sauna and the engineer had to replace the control valve.

Highlighted
Anonymous
Not applicable

Re: More Central Heating Woes

Well @pjmarsh it appears to be, it's a digital thermostat and when adjusted it makes the appropriate clicking noises in the right places. It also has an icon on it to tell the user if the boiler is On/Off and in this instance it is showing as off. But the continued heat supply to the control radiator is telling me another thing.

Highlighted
Anonymous
Not applicable

Re: More Central Heating Woes

That's a thought @SpendLessTime, I'll go and get a screwdriver (to use as a stethoscope) and have a listen to the pump.

 

Highlighted
Pro
Posts: 569
Thanks: 103
Fixes: 7
Registered: ‎30-07-2007

Re: More Central Heating Woes

Is the hot water system pumped or gravity fed (i.e. hot water from the boiler rises to the tank, and cooler water descends under gravity)? These rely on the boiler thermostat to switch on and off to control the hot water temperature and the boiler will often run when the pump is off.

If its this type, it's possible that you are getting a secondary/reverse flow back from the hot water tank to the hall radiator. Can you trace which pipes are hot. Does the hotter (inflow) pipe to the hall radiator swap sides depending whether the pump is running or not?

If the hot water system is pumped and thermostatically controlled, then check the thermostat on the tank. If it is faulty, then the hot water system may be demanding the boiler and pump run, and you are getting some reverse leakage from the hot water circuit into the hall radiator. 

 

 

Highlighted
Pro
Posts: 1,209
Thanks: 193
Fixes: 1
Registered: ‎11-01-2008

Re: More Central Heating Woes

There are so many potential issues and different arrangements of valves and controls that you would most likely get an accurate view of the problem by getting a central heating engineer involved.

However, your symptoms are similar to those I experienced in the past. Hall radiator does not have a thermostatic valve, and room thermostat is in the hall. Central heating was on a timer and on, but room thermostat was reading higher than set temperature, so should have switched off.

However, the hot water system was also on, but the water wasn't heating up because the diverter valve was stuck on 'heating only' position. So the pump and boiler continued to run to try to bring the water up to temperature, which it never achieved because all the flow was going through the hall radiator.

My other car isn't a Ferrari
Highlighted
Aspiring Pro
Posts: 573
Thanks: 54
Fixes: 3
Registered: ‎27-11-2012

Re: More Central Heating Woes

Is the boiler in a garage / outbuilding? We had a similar problem a few years back, the heating not shutting off automatically and the control rad going nuclear. Eventually someone had the bright idea of checking the frost protector unit by the boiler in the garage. On opening it up all the insides fell out in bits. New frost protector - problem solved

Highlighted
Pro
Posts: 1,097
Thanks: 131
Fixes: 5
Registered: ‎30-10-2011

Re: More Central Heating Woes

Do the burners shut down and the pump switch off when the thermostat switches to off?

Does the drawn hot water system work correctly?

Highlighted
Anonymous
Not applicable

Re: More Central Heating Woes

I can't listen to the pump like I thought I could. When I replied I had a mental picture of a red pump in the hall cupboard next to the hot water tank, but to my surprise on opening the cupboard it had been stolen! OK I say stolen but it hadn't I was confusing with my old house. So I don't know where or even if there is a pump in this system.

The boiler is in the garage so I'll venture out later to see what state it's in and maybe even turn it off to see if a 'reset' does anything for it. But I suspect I'll have yet another bill from the Gas Engineer coming.

Highlighted
Aspiring Hero
Posts: 2,847
Thanks: 847
Fixes: 82
Registered: ‎21-09-2009

Re: More Central Heating Woes

Yep, the newer boilers tend to have all the parts internal. So more part replacement jobs for the gas safe engineers. No serviceable parts now, all swap out a large expensive bit for another expensive bit.

I miss the old days of the big red pump sat on the boiler cupboard floor.

Highlighted
Superuser
Superuser
Posts: 7,994
Thanks: 1,677
Fixes: 107
Registered: ‎30-07-2007

Re: More Central Heating Woes

If the hot water system is pumped and thermostatically controlled, then check the thermostat on the tank. If it is faulty, then the hot water system may be demanding the boiler and pump run, and you are getting some reverse leakage from the hot water circuit into the hall radiator. 

 That sounds a likely cause if it's a fully pumped system. My system has always had reverse leakage though the bathroom radiator when the hot water is on, but that's actually quite useful most of the time!.

If the 3 way valve was stuck in heating mode, then all the radiators would be hot.

Any chance that the thermostat has been accidentally knocked and set to a very high setting ?

Highlighted
Anonymous
Not applicable

Re: More Central Heating Woes

Thanks for the input @SpendLessTime, you're not a Gas Engineer by any chance and you sure know how to cheer someone up. Wink

I don't have a clue what half most of this stuff means, all I know it that it's not functioning as expected. The thermostat is digital and it says the trigger temp is 22 and the hall temp is 25. I guess it might be duff but...

I've been out to the garage and did a power cycle on it, the water temp was at 53 at switch off and the burners were on. Turning it off then back on resulted in the burners coming back on and the temperature showing a rise.

So it looks like its one for the experts so I'll no doubt be hearing the rush of air through teeth as he thinks of a price he can get way with. Bummer.

Highlighted
Aspiring Hero
Posts: 2,847
Thanks: 847
Fixes: 82
Registered: ‎21-09-2009

Re: More Central Heating Woes

@Anonymous

Wish I was a gas engineer.

I tried to get my 3 kids to consider going into a trade (gas/electrician/plumber) and not one of them would even consider it. Given the money good ones earn (and a lot of bad ones too), I think they may regret it in future years

If I was 20 years younger, I'd retrain in a flash.

Highlighted
Community Veteran
Posts: 10,084
Thanks: 1,866
Fixes: 12
Registered: ‎02-08-2007

Re: More Central Heating Woes

@Anonymous

Is the pump not in the central heating boiler itself ? If you take the front cover off you should see it.

I assume, but could be wrong that all pressure systems had the pump inside the boiler, vented systems had the old red pump elsewhere on the central heating system.

@SpendLessTime

Looking back to train as a plumber, electrician would have been a good move, the ones I have known have never been short of work and in some parts of the country it can be difficult to get one (a good one) in an emergency.