Underfloor heating problem

[martinr007]

Hi,

Hoping someone can give some guidance as I'm at a loss.

I have a fairly new house (3yrs old) that has underfloor hearing downstairs and radiators upstairs. The system was provided by Invisible Heating Systems and installed by the builder, unfortunately Invisible Heating stopped trading about 3 days before my underfloor heating stopped working!

For some reason the tiles downstairs are cold but:
- the flow and return lines to the manifold are hot,
- the actuators on the manifold all seem to be working (go down when all thermostats are turned down and pop up when thermostats turned up),
- the pump sounds as though it's working (goes quiet when I turn down all the thermostats or when switch it off)
- the group flow valves? are open as the screw slot is vertical
- the return flow water temp is 10deg higher (70deg vs 60deg)

Th only thing is the water pipes coming out of the manifold are cold, it's almost as though something's jammed and not letting the water circulate. Also, my boiler isn't firing when it's just the underfloor on (upstairs radiators switched off during the day) its switched on but the burner light isn't on, the boiler lburner light only comes on when the upstairs radiators are calling for heat?

Sorry if this is all a bit long winded but I thought the more info I gave the better the chance someone might know what I'm on about I've been through the installation / pack that came with it without success.

Any help would be greatly appreciated,
Cheers,
Martin

 

[dcawkwell]

Is there a blending valve.

If the underfloor heating pump is working.
The pipe work to the underfloor heating is hot.

Sounds like a blending valve or another valve that is shut and not
allowing the flow of water through the underfloor.

 

[martinr007]

I don't think so but have attached a picture of the manifold.

After writing my earlier post I decided to switch every thing off, switched off power to the pump, turned down all the thermostats and opened and closed the group flow valves and closed then re-opened the boiler return valve.

After switching everything back on and turning up the thermostats it "seems" to be working!! The boiler burner light is now on, the pump is definitely running and the the water pipes below the manifold are getting hot which they definitely weren't before.

The only thing is that the flow and return temperature gauges have now dropped to 47 and 37 from 70 and 60 previously but they are rising. They've been sitting at 70 and 60 for the last 4 days or so even though the floor hasn't been hot so no idea about that.

One thing I never added in my first post and I'm beginning to wonder if it's relevant, my boiler has been needing topped up every 1 to 2 weeks for the past 3 months, I think the plumber said it's a stuck pressure relief valve, still waiting for a new one to arrive. I'm hoping there has been some sort of air lock due to the pressure bleeding down? and with me switching the lot off for 15 mins it's been sorted? heres hoping

Cheers,
Martin

 

[martinr007]

Sorry to bump this thread but, over the weekend my underfloor heating stopped working again. I thought it was because it was 12 deg and sunny during the day so never felt it, however it was 2deg outside last night and this morning the tiles were freezing.

As earlier, the manifold flow and return temperature gauges were reading 70 and 60 deg and the actuators were up, however the water pipes below the manifold were cold.

As previously I switched off the manifold control and pump and turned all the thermostats down, after an hour the flow and return temps had dropped by about 5 deg max (to 65 and 55deg). I then switched on the manifold control unit, turned up the thermostats and the pump immediately kicked in. The weird thing was that the flow and return temp gauges immediately dropped to 40 deg and 25deg!

The system is now working again and the temperatures are slowly rising. It's as though the system get's up to temperature but is going too high (the 70deg flow temp) and then shuts down. There is a sticker on the pump saying "safety stat 60deg"

I'm not sure if this means the safety stat on the pump is not working (don't think this is case because pump is shutting down) or if it's the regulating valve that's not regulating properly. It was set at 50deg (can't remember if this was how it was set or if my 3 girls have been playing with it!) so have reduced to 40deg to see if it makes any difference.

I definitely think I need to get a heating engineer that knows about underfloor heating systems but don't think there are many round my neck of the woods so any help to point me in the right direction would be greatly appreciated.

Cheers,
Martin

PS A photo of the manifold, I forgot to upload the last post

 

[martinr007]

Photo of the manifold

Untitled

• martinr007
• 19 Mar 2012
• 1

 

[mysteryman]

Lowering the setting of the blending valve has almost certainly solved the problem. The limit thermostat is there to stop the pump if there's an overheat.

 

[martinr007]

Ok fingers crossed, although I would swear it has always been set at 50 deg on the valve.

Cheers,
Martin