Strange underfloor heating issue

[Mattsp]

Hello, I’m living in a new build, approx 6 years old, with underfloor heating. Up to about a month ago everything was working well, and the house was toasty.

 

Over the last month, the downstairs floors are failing to heat up. When I look at the manifold, there is hot water at 50 degrees coming from the boiler, but all the return flows for all circuits are cold. All of the circuits are calling for heat and never get up to temperature. I got a plumber out, he replaced the pump on th manifold, that has made no difference at all. Next I flushed all of the circuits to remove any air, again this has made no difference. As a final test, I have closed all but one circuit and am waiting to see if that heats up. Failing that I am at a loss as to what the problem could be and am looking for some advice.

 

regards,

 

matthew

 

[joe90]

Like your plumber i think it looks like a flow problem (hence the pump replacement) my manifold has flow indicators on each loop, can’t see any on yours?

[Temp]

Stuck pins? 

 

If the loop you are testing doesn't warm up try removing the actuator head and seeing if the pin will move.

[nod]

I’d a similar problem with three zones 

Peter W on here kindly talked me through any flow issues

I’d three zones working fine So was able to rule out pump 

As temp as already stated swapping the actuators and making sure the pins are free is a good place to start I see you have one working 

Mine turned out to be a broken wire in one of the strats Simple fix to a big problem  

[Mattsp]

Thanks for the comments, all of the actuators do work/open up, I just switched off all but one zone as a test.

 

All of the actuator heads open up, I proved this when I flushed each zone through with clean water.

 

Unfortunately my manifold does not have flow indicators, so I cannot detect if there is flow through the system.

 

So am now looking for other suggestions to help me diagnose this issue?

 

thanks! 

[Temp]

6 hours ago, Mattsp said:

Unfortunately my manifold does not have flow indicators, so I cannot detect if there is flow through the system.

 

 

The flow and return manifolds both have hose ports. Perhaps you could rig up a temporary loop between the two? That would confirm if the pump and any valves or mixers are working.

 

 

[Mattsp]

Thanks for the suggestion, sounds sensible, I will try and report back

 

matthew

[Mattsp]

Just an update in this issue, I realised that the 2 port Honeywell valve for the downstairs heating wasn’t opening when the ufh system was calling for heat. I have replaced the actuator head of the valve and we are now back all nice and toasty!

 

thanks

 

Matthew