Central Heating not heating rads, but is heating hot water cylinder

pan

Hi Guys,

Need help diagnosing this problem!!

My system seems to be a open system (two tanks in attic, plus no top-up valve in hot press)

The boiler seems to be working fine, it's heating the water cylinder in the hot press but failing to reach any of the radiators??

The boiler is an Ideal Classic FF340
The water pump above boiler is Ideal MP53

Do you think the water pump is faulty? I can hear it working(I think)!

oh, the flash programmer is set to HW + H

Thanks in advance, pan

311

It sounds like you have a motorized valve somewhere and it's not working.
In order to have hot water only with a pump for heating ,there would have to be at least three pipes from your boiler.

pan

Thanks 311,

My system seems to look like this

http://www.muswell-hill.com/foxandco/pages/howdoesitwork.htm

Yes, there is 3 pipes at my boiler, 2 seem to be coming in and 1 going out.

It makes sense that this is a Motorised value problem, but I can't find it? What should it look like? Should it be in the hot water press?

thanks again
pan

311

Normally the motorized valve would be in the hot press ,but it can also be located near the boiler/ under the floor above the boiler.

It's like a small box attached to a pipe. Some have a small slider ,so you can manually open them.

pan

Found it just above the boiler!
It a sunvic sz2301. spring return type
Ive removed it from the valve and manually open it and the rads are working now. There is a lever on the sunvic that says flush (manual open I suppose).

What should I do get this motorised switch replaced? Or can I put it back on and leave it in the manual flush position?

Thanks

DublinWriter

pan wrote: »

What should I do get this motorised switch replaced? Or can I put it back on and leave it in the manual flush position?

Sounds like the system we have.

If you were confident enough to remove the value then you should be able to replace it yourself. I don't claim to be an expert, but if you're buying a replacement then check out what the switch is rated for pressure-wise. Most cope only with 1-2bars of water pressure.

311

pan wrote: »

What should I do get this motorised switch replaced? Or can I put it back on and leave it in the manual flush position?

Thanks

Normally you would call someone like me :eek: ,what you've done so far is what I'd tell someone over the phone.
Theres nothing wrong with leaving the valve open . If your happy with that for the moment ,get it fixed the next time you have your boiler serviced.

It's up to you:)

youtheman

Your problem might not be with the actuated valve. You need to confirm if it's getting an open signal from your controller. If it is they it's the actuator.

But you may have a problem with the thermostat, the controller, or the wiring. You need to eliminate these before you can be certain it's the actuated valve.

landydef

if you can manage to track down the same type of motorized valve you might get away with just replacing just the head (electrical part) of the valve as opposed to the head and the mechanical part
the advantage of this is that you wont have to drain down your heating system
although it could also be a problem with your room stat or even your clock so might be worth getting a plumber with decent electrical knowledge to check it out before you replace anything

AoifeK

Hi, I have exactly the same problem. The light on the valve for the hot water is on, and I have hot water, but the light on the valve for the radiators is off and I've no heat - brrr.
How exactly did you remove the valve? Did you simply unscrew it?