Has my heating controls been wired wrong?

[SteveP86]

Hello everyone.

Bit (quite a bit) worried that something bad is going to go wrong with my boiler.

I've finally moved home to a house with a Baxi Inset 50/4 Bermuda back boiler and found that the timer on the controls wasn't working. I called out a local plumber and got a new digital programmer which is great as the old one only had two on times where as the new one has three. I can't honestly say that this fault has been here all along as I was only in the house a few days when I got the new timer installed but what I've noticed happens is when the thermostat in the hall clicks off, I can hear the pump shut off however the boiler still stays lit, starts to bang like hell then shuts off followed with louder banging then eventually settles down.

To replicate the fault and with a cold system I set the hall 'stat to 10 deg (ie clicked off) and turned the boilers own 'stat to 0 and switched the programmer on to call for heat.

Now I'm no expert but I would expect nothing to happen when I slowly turn up the boiler stat as the hall one is still thinking it's hot enough and not clicking on. What happens is the pump does nothing yet as soon as I turn up the boiler one the thing fires up then after a short while bangs then cuts off. (guessing perhaps over heat protection?). I thought if anything the boiler would switch off first then the pump a few seconds later to remove heat from boiler and not other way around?

To satisfy my worries a bit and to keep using the system till I figure out what to do I've set the hall stat to 30 deg so basically the whole time the heating is on the pump will be on continuously. The water gets up to temp, the boiler shuts off and the pump keeps pumping then when the timer turns off so does everything else and no loud banging.

So, good people of DIYnot... what do you recon? Is this normal or should I get someone out to check things out?

Many thanks for reading

PS..

Old timer is a Horstmann 425 I think (looks the same)
New one looks like a drayton LP522 (again, looks the same)

Steve

 

[picasso]

Your boiler is probably set up for gravity hot water and that is why the boiler is coming on without the pump running, have a look near your hot water cylinder for a valve on the pipework as it could be a fully pumped system but been miswired.

 

[twgas]

If you've just moved in it would be wise to get the boiler serviced.
Check there's some water in the f&e tank (small one in loft)

 

[SteveP86]

Your boiler is probably set up for gravity hot water and that is why the boiler is coming on without the pump running, have a look near your hot water cylinder for a valve on the pipework as it could be a fully pumped system but been miswired.

I noticed in the manual there's a jumper setting for changing between gravity and pumped. Obviously there is a pump there and as I type this the boiler is turning on and off without a peep as the pump is running. IF this is a gravity system and the jumper is set to gravity and I change it to pumped, could I damage anything?

Pump is well hidden under floor in bedroom and would entail moving everything out to pull the carpet so not too sure about the presence of valves and certainly not any in airing cupboard with tank. I can have just HW or HW/CH and pump is on for heating but if I ask for just HW then boiler fires and I hear no pump... followed by BANG from boiler. This was a DIY install back in 70's so perhaps installer didn't realize pump etc should perhaps be a little more accessible?!?

Steven

 

[Whitespirit66]

To replicate the fault and with a cold system I set the hall 'stat to 10 deg (ie clicked off) and turned the boilers own 'stat to 0 and switched the programmer on to call for heat.

Now I'm no expert but I would expect nothing to happen when I slowly turn up the boiler stat as the hall one is still thinking it's hot enough and not clicking on. What happens is the pump does nothing yet as soon as I turn up the boiler one the thing fires up then after a short while bangs then cuts off

If you do the above, but with the cylinder stat turned right down, does the boiler still fire?

Certainly an odd one and sounds like wiring could be wrong.

 

[SteveP86]

To replicate the fault and with a cold system I set the hall 'stat to 10 deg (ie clicked off) and turned the boilers own 'stat to 0 and switched the programmer on to call for heat.

Now I'm no expert but I would expect nothing to happen when I slowly turn up the boiler stat as the hall one is still thinking it's hot enough and not clicking on. What happens is the pump does nothing yet as soon as I turn up the boiler one the thing fires up then after a short while bangs then cuts off

If you do the above, but with the cylinder stat turned right down, does the boiler still fire?

Certainly an odd one and sounds like wiring could be wrong.

Sadly no Cyl Thermostat

Steve

 

[twgas]

Check there's some water in the f&e tank (small one in loft)

I say again, although it could be air lock or blockage........

 

[SteveP86]

Check there's some water in the f&e tank (small one in loft)

I say again, although it could be air lock or blockage........

Hi twgas

f&e tank at correct level ie water pushing against ball valve, not too low or high.

also boiler got serviced at same time as new timer fitted and was told boiler looked great for a 17 year old

Steve

 

[twgas]

Does your HW work properly, sounds as though you have circulation problem in your primaries.

 

[SteveP86]

Does your HW work properly, sounds as though you have circulation problem in your primaries.

if the CH is on at the same time yes. If CH is off and Hw on then no pump action and just boiler