UFH Diagnosis

[Paul Ashley]

Good morning all

 

I have a UFH system, which was inherited when house was purchased. It was originally designed to run on oil but I now have an ASHP, which provides the hot water to the system.

 

The system is run with Weather Compensation at the ASHP controller and although the system originally had multiple zones wired via Heatmiser UFH8 and neoAir room thermostats, the thermostats are all set way over target temperature so that they are always calling for heat and only the external air temperature is determining the flow temperature through the system, meaning a completely open system.

 

There are 2 manifolds, one is around 2-3m of pipe run from the ASHP piping and the other is around 25m from the ASHP piping.

 

My question is based on the difference in temperatures seen at the manifold compared to the flow temperatures at the ASHP controller. The photos I attach show the controller where the target flow temperature is 38C and the actual flow and return are 38/33 which looks fine. 

 

However, at the manifold with an open system, I would have expected to see higher flow temperatures and certainly no differential in the return temperatures between loops. What could be happening and how can I alter this? How with the flow temps at the manifold, is the ASHP controller showing 33C when the temps at the manifold are lower than this?

 

It seems like the ASHP is doing what it is supposed to but something is not right with the UFH.

 

Help appreciated

 

 

[JohnMo]

26 minutes ago, Paul Ashley said:

ASHP controller showing 33C when the temps at the manifold are lower than this

That's mixers, they mix, they mix all the time like it or not, always a fixed amount of mixing. They are really designed to operate with high flow temps from boilers, generally not suited to ASHP systems. If you need to mix because of different flow temp needs for two different manifolds it's better to use an electronic mixer driven by the heat pump controller.

 

I had the same issues, deleted the mixers and additional pumps, the actuators on the manifold and just left room sensors in place for monitoring.

[Paul Ashley]

Thanks JohnMo - I was thinking that now that I am running an open system I should get rid of the mixing valves and actuators and shouldn't need any pumps anywhere and just let the ASHP's pump push the water around the system. I have different temperature requirements though in different rooms (because of different levels of insulation and weather exposure) so presumably I need flow valves to enable me to regulate at the manifold rather than actuators. Is that correct? 

 

Regards