Boiler and pump randomly firing up!

[ianc1990]

Hi,

I have recently purchased a house and I have sometimes noticed that despite the programmer having both the HW and CH turned COMPLETLY off, the heating randomly fires up sometimes and heats up the radiators for 30 mins-1hr. The circulation pump also comes on and stays on for the overrun period, as if I had turned the CH on manually.

Does anyone have an ideas as to what could be causing this problem?

The setup is a Drayton LP552 programmer, 1 single thermostat and a GloWorm 30FF boiler.

Thanks

 

[ukrobj]

May be a fault with the programmer, but as youve just moved in no history, tried turning the room thermostat right down and see if it stops it.


Depending if you have a y or s plan system, may be an issue with a motorized valve.

You say its random, is it completely random or is it at certain points (mornings or evenings etc)

 

[ianc1990]

Hi,

I'm not too sure I'm afraid as we haven't moved in yet but I will certainly keep an eye on it!

I will try the thermostat if it kicks in again to see if this stops it.

Its a Y plan system - is it possible that the problem is with the Valve (a Honeywell sundial Y plan valve?)

If it was the valve, I would expect that the system would simply stay on if I turned if off but the programmer has been set to OFF on both CH and HW for over a month now so I do not see this being the issue if my thinking on the valve is correct?

I have very little knowledge on central heating but just trying to work this out from what I have read online.

Is there a way to test the valve if this could cause the heating to randomly turn on?

 

[ukrobj]

Just a random thought, the other thing that may be making it fire if its got a frost thermostat somewhere on the system or a frost pipe thermostat if its run via a garage etc. i know its not that cold but if its been knocked it might be a cause.

 

[ianc1990]

The boiler itself doesn't have frost protection as far as I understand but it could very well have a frost pipe thermostat as the boiler is installed in the garage.

Any chance you could tell me where I would expect to find this and what it looks like?
I haven't been in the garage for a while and as you said, its been +10 degrees whenever I've been in the house so I doubt this is the issue.

Would a frost pipe thermostat turn the heating on for such a length of time allowing the radiators to get so hot?

Thanks for your help.

 

[ukrobj]

Wll look something like that on the pipe

or

 

[ianc1990]

In that case definitely nothing there unless its somewhere between floorboards inside the house (which I expect its not otherwise it would defeat its point?)

Is there any way I can test the Y valve as I understand this could be causing the problem? Or is this not the case if it randomly fires itself up at random times?

Is there also a way I could test the programmer?

Cheers

 

[ukrobj]

Try that, follow the fault finding steps on the right.

Untitled

• ukrobj
• 14 May 2012
• 9

 

[ianc1990]

Thanks - is that the wiring for the programmer (in the centre)

Im a little confused with some of those steps - not sure what it refers to with TB6 TB Orange Wire, TB7 MPV, etc.

The other ones are obvious (Rstat, Cyl Stat, etc)

Thanks

 

[ukrobj]

the center strip is a Terminal Block (TB) the number after that relays to the location on the terminal block.

The programmer is below that to the left.

If in doubt, get a heating engineer to take a look, they will understand this quiet well.

 

[ianc1990]

Thanks

I might just change the Y valve electronics as I can get hold of the honeywell replacements quite cheap.

Can you let me know if its possible that this is the problem if its sticking or will this only be an issue if the heating had to stay on, after it was turned off?

Do you have an idea as to how much it would cost to get it investigated?

 

[ukrobj]

you could be getting some backfeed from the cyl stat/programmer. Cost wise, could be anything from £50-150.

 

[ianc1990]

Hi,

Just managed to find a Honeywell FrostStat installed in the garage - never spotted it.

Is it possible that the frost stat kicks in at around 10 degrees and there is no pipe stat so it stays on for a long time?

Where would the pipe stat normally be installed if I have one and should I be putting one in if there isnt one there?

Thanks!

 

[ukrobj]

Your response doesnt make sense, you say you found it in the garage, then you saying where should your pipestat be if you havent got one.

I suggest with the greatest respect call an expert in.

 

[ianc1990]

Hi Rob,

My response may not have been very clear.

I found a Honeywell frost stat which is installed above the boiler (just above the roof line) of the garage.

However, there is no pipe stat installed on the return pipe.

Therefore, I believe that my issue is that the garage is getting cold, and the boiler kicks in indefinitely (or at least until the garage ambient temperature warms up one way or another - this currently only takes around 1 hour as its not very cold outside)

Therefore, I think my next step should be installing a pipe stat on the return pipe of the boiler so that it can cut out the boiler once the pipes reach the set temperature on the pipe stat.