Back Boiler Pump

[heheshamon]

Hi I have an old back boiler and have just invested in a Drayton T720R with remote stat I don't think this is related but I will mention anyway just in case, I had a bit of a nightmare fitting it as the instructions were rubbish and it was a case of trial and error for a couple of hours, it turned out that I needed to link the old thermostat cables and the heating and hot water text on the unit where the incorrect way round.

Anyway back to topic I have noticed that the pump keeps running when the heating is off and was concerned that there is an issue I have played around turning it on and off and you can clearly hear the pump coming in and out.

all the rads are bleed but there does seem to be a slight knocking sound coming from the boiler all rads are getting hot and water is up to temp.

Is this something to do with the programmer (is there some other wiring required) or is the pump on the way out.

if I do need a new pump are they available the solenoid failed about 12 months ago and everybody even Honeywell said they were obsolete but managed to obtain one from a Honeywell valve off the internet so I'm worried that I'll have the same issue with the pump, there's nothing that concerns me with the boiler it heats the house and water it may cost me a bit more to run each year but it's a very simple unit, my friend has spent loads on his new combi boiler and it's only 6 years old with new circuit boards etc.

i appreciate your help.

Simon

 

[heheshamon]

Just to clarify that the pump stops when the water is switched off.

 

[Rckape]

It's probably your zone valve. In your airing cupboard you should have either a two or three port valve. The motor inside the actuator heads wear out.

Depending on the valve you have it could be a simple fix by just replacing the motor, or it may need the whole valve replacing.

If your unsure about how to do this then it's time to call a plumber who will sort it pretty quickly.

And for future reference, you wouldn't have to match the pump like for like. A new one off the shelf as a replacement would do the trick.

 

[heheshamon]

Right I'm nearly there its seems to be a wiring issue with this new stat I've redone the programmer so that the pump comes on when the rf stat calls for heat, but now theres another issue the burners wont stop on the hw program.

Ahhh head ache any help?

Shouldn't the stat on the boiler stop the burners?

 

[stani]

Have you got a zone valve? Old back boilers were usually gravity circs and then pumped heating, where turning the pump on was How you got water around the heating.

 

[heheshamon]

Thanks for the reply, after hours this evening trying different wiring configs I've got to the stage that I believe the fault is.

The new T720R seems not to like the wiring if I set the stat on one side of the programmer it calls the burners but the pump runs on HW but if I set the stat on the other side it works the pump on and off with the CH but wont call the burners.

I've left it on continuous pump due to the weather but I'm sure this wont be good for the system.

HELP!!!!!

 

[stevetheplumber]

if its gravity you would use hw to fire the boiler and heating to fire the pump when hot water is called for the boiler will light and be controlled by the boiler stat