Why isn't my heating working

[FloppySock]

Hi all,

I'm driving myself mad trying to figure out what's preventing my radiators from heating up. I moved into this property a couple of weeks ago and am currently renovating the whole place. This is the first time I've done proper DIY stuff and I've read up a lot on plumbing & heating, including the manuals for all the devices in the house that I can find.

The heating worked on the first day but since then it's been dead. I've been tracing pipes and lifting floorboards to make sure I fully understand the system. It's a gravity fed system with the hot water tank in an airing cupboard and the cold tanks above.

Boiler: Baxi Solo 40/4 RS (old I know!)
- No problems with the hot water
- Pilot light stays on fine
- Fires up when adjusting the heating thermostat on the wall but only stays on for a minute or so then goes off

Heating pump: Grundfos Alpha 2 15-60 (recently replaced as the old one didn't seem to be spinning)
- I've traced the pipe from the boiler to the heating pump (annoyingly under the floorboards in the centre of the back bedroom). The pump powers fine and I can hear it humming away so it seems to be operational
- Pipes coming from the pump split off to what I assume are the radiators
- Pipes leading to the pump never get hot (which I expect they should) - water must be getting to the pump though as when I remove the pump from the pipework there is water inside.

One thing I can't find is a motorised valve. Do all systems have them and where would I expect it to be located? After the boiler but before the heating pump? It may be in the roof space of my kitchen extension where the boiler pipes shoot upwards into.

EDIT: when the boiler seems to go off there is a lot of clunking and clanging of pipes before hand. Is this the heated water going nowhere and the boiler powering down to avoid overheating? Is it the elusive motorised valve failing?

Any advice would be wonderful.

Cheers,
Phil

 

[Gasguru]

When you only have the hot water on does the pump run?
What size are the pipes from boiler to cylinder...28mm?
If the cylinder is heated by gravity circulation you won't find any motorised valve.
Sounds like a blockage somewhere...
On the tick box paperwork what did the vendor say regarding the heating system working ok?

 

[FloppySock]

When you only have the hot water on does the pump run?
What size are the pipes from boiler to cylinder...28mm?
If the cylinder is heated by gravity circulation you won't find any motorised valve.
Sounds like a blockage somewhere...
On the tick box paperwork what did the vendor say regarding the heating system working ok?

Thanks for getting back to me Gasguru.

1. Pump doesn't run when hot water is on
2. GF and GR are 28mm, PF and PR are smaller
3. Images of pipes attached. Does this mean there is definitely no motorised valve as the heating and hot water have separate feeds? I've found some odd set ups in the house so far (unrelated to plumbing) so always a chance whoever installed things has some non-standard stuff.
4. Is clearing a blockage something a home DIYer can do or will I have to call in the professionals?
5. As far as I remember there was no cause for concern. And I believe the heating worked on the first day in the property - probably the first time it had been fired up in a while as no one was living in the property for a good 5 months previously.

Thanks

 

[Gasguru]

If your pump and radiator valves are open it can only leave a blockage.
You may have an anti gravity valve on the pipework to prevent heat rising from the boiler into the heating circuit (when only the hot water is selected)...this could be stuck.
Sometimes the the pumped circuit connections onto the boiler have inserts to promote gravity circulation...the manual doesn't mention anything but it's possible there's a blockage there.
Try a magnet on the pumped circuit..otherwise it's time to cut up the pipework to find it.