Sometimes hot, sometimes not. What could be the cause of our erratics heating?

[BNM]

It's like this. Sometimes our radiators are very hot, usually they're just tepid. Sometimes the hot water from the taps is very hot indeed, other times it's hand-hot. We've had plumbers round who've checked everything and can find no faults. (Everything's working just fine when an engineer visits. Typical.)

[FONT=Helvetica Neue, Helvetica, Arial, sans-serif]All the rads have been bled and the boiler (an Ideal something-or-other) recently serviced. The plumber suggests a powerflush. He reckons that there might be a build of sludge in the system. But the quote is close to £500 and I'm reluctant to give the go-ahead when a power flush only 'might' be the solution. In any case, how can a build of of sludge make the heating perform so erratically? [/FONT]

Can any of you bright people think of any other possible causes? We're tired of waking up to a room that's about 14 degrees C.

 

[SimonG]

Is it a combi boiler?

 

[chris watkins]

Is it a combi boiler?

or does your hot water come from a cylinder ?

Can you describe you heating system & controls, do you have TRV's (Thermostatic Radiator Valves) fitted to all the radiators, do you have a room thermostat & time clock / programmer installed ?

How old is the system ?

A bit more info please.

 

[BNM]

or does your hot water come from a cylinder ?

Can you describe you heating system & controls, do you have TRV's (Thermostatic Radiator Valves) fitted to all the radiators, do you have a room thermostat & time clock / programmer installed ?

How old is the system ?

A bit more info please.

Hello. Yes, the hot water comes from a cylinder. There's a thermostat on that which normally reads 55 degrees. I've raised it to 80 and it's had no effect. The heating and HW control panel/programmer seems to work OK. The house has 15 radiators of which just one has a TRV fitted. The room thermostat has always been a bit suspect: you can set it to whatever you like (I choose 21 or thereabouts) but move the dial and the 'click' always occur at around 13 or 14 degrees. (That's unless the ambient temperature is pretty warm anyway, in which case it's less important that the rads are working at 100%.)

The system itself dates from the neolithic age but the boiler is about 15 years old, tops. A bit of history: about six weeks ago the heating wasn't coming on when it was supposed to. I discovered that the way to make it fire into action was with a bit of primitive engineering - I gave it a whack. A local plumber determined that a new control panel for the boiler was what was needed. Since then - but not from that very day - the CH and HW have been acting up, but the same plumbing firm have been back twice and found nothing wrong.

However, last night I found that I was able to put my hand on any of the pipes coming out of the boiler without scalding, so I'm thinking that the problem is definitely there, rather than being attributable to a build of sludge as the plumber maintains. Maybe they installed a dodgy control panel. Maybe that's it.

And maybe a new room thermostat, too. Do they go wrong?

 

[SilentMike]

could be any number of things or more than one by the sounds of it. Sounds like you have no confidence in you previous plumbers
i would get someone else in to diagnose the problem
you could try the i'am looking for a plumber section on here to see if anyone is local.
and i would turn your cyl stat back down to 55 too

 

[chris watkins]

I am afraid that Mike is right it could be a number of things & we would have to be on site to find out exactly but lets reduce it a bit.

1. You are correct in thinking that it is very unlikely to be sludge, even though, it like me, has been around for a long time it is very unlikely to just suddenly need cleaning after the plumbers first visit.

2. Turn the thermostat on the cylinder back down to 55 - 60 as Mike suggests, as this only controls the temperature of the hot water that comes out of your taps.

3. When you say the boiler control panel do you mean the programer? the thing that you set to turn the heating &/or the hot water on and off or do you mean that it was part of the boiler itself that was replaced?

4. You could just try putting the heating only on "continuos" (24hour), turn the boiler thermostat (the temperature knob on the font of the boiler) up to max (5), turn the room thermostat up as well & leave for at least a couple of hours. If it gets nice and warm we know it is not a circulation problem, after this time you can turn it off & stats back to normal settings.

Come back and tell us what happened.

 

[zzzjim]

Is HOT water tepid in cold weather ?

Chris Watkins " list of things to try " is good !

 

[BNM]

I am afraid that Mike is right it could be a number of things & we would have to be on site to find out exactly but lets reduce it a bit.

1. You are correct in thinking that it is very unlikely to be sludge, even though, it like me, has been around for a long time it is very unlikely to just suddenly need cleaning after the plumbers first visit.

2. Turn the thermostat on the cylinder back down to 55 - 60 as Mike suggests, as this only controls the temperature of the hot water that comes out of your taps.

3. When you say the boiler control panel do you mean the programer? the thing that you set to turn the heating &/or the hot water on and off or do you mean that it was part of the boiler itself that was replaced?

4. You could just try putting the heating only on "continuos" (24hour), turn the boiler thermostat (the temperature knob on the font of the boiler) up to max (5), turn the room thermostat up as well & leave for at least a couple of hours. If it gets nice and warm we know it is not a circulation problem, after this time you can turn it off & stats back to normal settings.

Come back and tell us what happened.

Hi Chris

I should have said PCB, not boiler control panel. It's a non-user bit of kit that goes inside the boiler. The heating has been on since dawn and, while none of the rooms have reached what I'd call room temperature (20 - 22), it's not teeth-chatteringly cold either - most rooms seem to be around 17 - 19. The outside temp is 8, the room thermostat is set to 25 but 'clicks' at 13/14. The rads give off different levels of heat but none is too hot to rest your hand on.

The boiler thermostat has been set to 6 - the maximum - for a week or more. The anti-frost thing is set at +1. The pipes coming out of the boiler are hotter than they were last time I checked but I can still grip them without pain.

It seems to me that whatever the problem is, it's affected by the ambient temperature. If it's not that cold (and +8 isn't THAT cold) then the CH system performs a little better (though not as well as it should, even in a single-glazed Victorian house like mine). But when it's proper cold outside, as it's predicted to become later this week, the rads will only achieve varying degrees of lukewarmness.

I'm sorry I can't provide anything more than a layman's description of what's going on.

 

[chris watkins]

No thats good and a bit more to go on now, if they have replaces the PCB in the boiler & the problems only started around that time then you need to call them back as it is likely to be the new board or connections to it.

If the boiler stat is set to Max then any boiler should heat the water going around the heating system to around 80deg C, if you have had it on for that amount of time & can hold on to the flow pipe out of the boiler its more like half that & will not heat the house when the outside temperature drops.

Phone them in the morning ask them to come back & sort it out.

 

[BNM]

No thats good and a bit more to go on now, if they have replaces the PCB in the boiler & the problems only started around that time then you need to call them back as it is likely to be the new board or connections to it.

If the boiler stat is set to Max then any boiler should heat the water going around the heating system to around 80deg C, if you have had it on for that amount of time & can hold on to the flow pipe out of the boiler its more like half that & will not heat the house when the outside temperature drops.

Phone them in the morning ask them to come back & sort it out.

Thanks Chris. Yes, it's worth getting them back, especially as the part cost £140 plus labour. I'm predicting an argument, though. If they refuse to sort it I'll name and shame...

 

[chris watkins]

Better still just mention what you have told us i.e. it was working OK before you replaced the part & it not now. If that is the truth and they don't come across try trading standards. I take it you checked to make sure the engineer was Gas Safe ??

Just as a matter of interest why did they need to replace the PCB?

 

[BNM]

Better still just mention what you have told us i.e. it was working OK before you replaced the part & it not now. If that is the truth and they don't come across try trading standards. I take it you checked to make sure the engineer was Gas Safe ??

Just as a matter of interest why did they need to replace the PCB?

Hi Chris. Yes, they are Gas Safe. About two months ago, the CH and HW wouldn't come on at all at the designated time. I investigated and the boiler was doing nothing. I opened the hinged flap to take a look (not that I expected to see anything out of the ordinary, or be able to fix it if I did). But when I shut the flap, the boiler burst into life. I repeated the action the following day to make sure it wasn't a coincidence and the same thing happened. The engineer identified the culprit as the PCB and replaced it a few days later.

I think they might have replaced one faulty PCB with another one.

 

[chris watkins]

Hi Chris. Yes, they are Gas Safe. About two months ago, the CH and HW wouldn't come on at all at the designated time. I investigated and the boiler was doing nothing. I opened the hinged flap to take a look (not that I expected to see anything out of the ordinary, or be able to fix it if I did). But when I shut the flap, the boiler burst into life. I repeated the action the following day to make sure it wasn't a coincidence and the same thing happened. The engineer identified the culprit as the PCB and replaced it a few days later.

I think they might have replaced one faulty PCB with another one.

or there was /is a problem with the wiring / connection not the PCB, get them back !

Good luck & please let us know how you get on.

 

[BNM]

or there was /is a problem with the wiring / connection not the PCB, get them back !

Good luck & please let us know how you get on.

I will. Just noticed that I wrote 'erratics' in the question, which mortifies me almost more than our dodgy boiler!

 

[zzzjim]

I wrote 'erratics'....................!

Don't worry Too much TV watching .. I think I understand Merkat now !

 

[BNM]

Don't worry Too much TV watching .. I think I understand Merkat now !

Update: The original plumbers came back with a brand new Thermistor, which they'd decided was the problem. When that didn't work they suggested a new PCB. 'What, another one?' I asked. He was unaware that the PCB had already been replaced. He thought for a while and then said that in that case it must be the knob on the front of the boiler. Well, not exactly the knob, but all the electrical gubbins behind it. So he's ordered one of those.

My boiler is getting like the Ship Of Theseus. [I tried to link but this site is having none of it!]

Meanwhile, I am burning coal like it's going out of fashion. Which it is, of course.