Underfloor Heating Weird Behaviour

[Maxwell_Montes]

So my UFH only gets warm once the thermostat calls and the pump is off.

 

my plumber has tried to convince me that UFH is slow to heat up and that’s what I’m experiencing. This is not the case.

 

When it’s on, the flow pipe is hot and the return pipe is cold. As soon as I stop it calling for hot water, the return pipe gets warm and the floor starts to heat, but if I left it on all day it would stay cold.

 

any ideas what is causing this behaviour?

 

I’ll upload a picture as the manifold isn’t standard, showing how the hot water is flowing.

 

Although it isn’t the usual configuration, supposedly it *should* work but I wonder if the flow valves being on the return arm is the issue(?)

[ProDave]

What is the heat source?  Boiler or heat pump?

 

Is it new, or old? Has it ever worked properly?

 

So flow and return from heat source go direct to manifold via that 2 port valve.  So I can see without the manifold pump running, the system pump will push water through the UFH pipes.  There is a TRV that appears to open / close to regulate UFH temperature.

 

That pump would indeed appear to bypass the UFH loops.  I think that is a thermostat top right grey box? What does that turn on and off?

 

Who configured the manifold like that and why?

 

The wiring suggests whoever did it may not be the best and may not know what he is doing?