Problem with heating

[mark306]

Hi,

We are having a problem with the central heating I'll try and describe the symptons.

1) Boiler make / model (gas or oil)
Potterton PrimaF / gas

2) What is / is not happening.
If the programmer is set to turn on the heating and hot water at the same time the water gets hot but one of the radiators downstairs remains cold.
I can see the CH and DHW lights LEDS are on. I suspect the Circulating Pump isn't working.

If I turn the hot water off on the programmer (just the CH is displayed on the Motorised valve) this time the pump seems to activate and heat all the radiators.


3) Has ANYTHING else been done or changed recently.
Nope being doing this for as long as we've been in the house (2 years)

4) When did the problem start?
when we moved in

5) When does it happen? eg, heating coming on or going off.
See 2

6) Anything else you feel may be of relevance.
see 2

I'm not really sure what's broke here can someone help. I will provide more inofmraiton if it'll help.

Thanks
Mark

 

[seco services]

wouldn't suspect the pump if only one rad cold.
what speed is the pump on ?

 

[mark306]

The pump is set to 3. The reason I don't think it's working is because when just the CH comes on I can hear the water knocking around in the pipes quite loudly. That doesn't happen when the CH and DHW is on...

 

[seco services]

take the screw out the centre and you can check if its working with heating
or check to see if it getting power when heating on.

it may be loosing its will to live.

 

[mark306]

I can only see the big bolt in the middle is this what you mean?

 

[gas4you]

Yes unscrew that and pull it gently forward. This should lock it into the 'spindle' to let you try to turn it.

 

[mark306]

now I'm really confused, which doesn't take much when it comes ot DIY. I removed the plastic cap and there was a little metal thing sticking out and there is a little bit of water...
How can I test if the pump is actually working from this?

 

[seco services]

as said you can pull it forward and it will lock into the splindle and with heating running it will rotate.

 

[mark306]

Well it's spinning with the two different combinations so I assume this means the pump is working...

 

[mark306]

I just wonder if it could be the myson Motorised valve. Does anyone know how this works? Maybe it's semi-blocked when set to CH and DHW on? Could this explain why the one radiator isn't hot... clutching at straws really I'm sure I'll have to get a plumber in but want to understand the problem!

 

[seco services]

have you got a gate valve on the cylinder return pipe ?

 

[gas4you]

Do you have a TRV on this rad? If so remove the head and check the pin has not stuck down (shut)

Turn off the HW, shut any by-pass valve you may have, turn on the CH and turn off all rads except the one that is cold.

 

[seco services]

Do you have a TRV on this rad? If so remove the head and check the pin has not stuck down (shut)

Turn off the HW, shut any by-pass valve you may have, turn on the CH and turn off all rads except the one that is cold.

its only cold when hw/heating on.
hot with only heating on.

thats why i suggested that the cylinder maybe nicking the flow.

 

[gas4you]

That'll teach me not to read through the OP properly. I have a short attention span when it comes to long posts

I have had a lot of these heads go strangely faulty, never been very impressed with them.

OP what happens if you set valve to manual? The same as both on?

 

[mark306]

have you got a gate valve on the cylinder return pipe ?

which one is the cylinder return pipe?