Heatmiser UH1-W + air-source heat pump = no heating! HELP!!

[LB13]

I've had a wet underfloor heating system installed with the UH1-W Heatmiser control system and wireless room thermostats. The hot water is provided by an external air-source heat pump (ASHP) - the controls and hot water cylinder are in the (attached) garage.

When I turn a thermostat up in one of the rooms it takes ages for the flow pipe to the manifold to begin to warm up, and then even if I'm lucky enough for it to actually get hot, within about half-an-hour it goes cold again.

The ASHP installers have been back to check their system, and say it's ok. The builder who installed the underfloor heating has had a breakdown (!) and other than sending a plumber to confirm that the pipes have all been connected properly, is doing nothing to help.

Does anyone have any suggestions please?

 

[Agile]

Has this ever worked properly?

It does sound like a controls problem and presumably that's the responsibility of the ASHP installer. Many are not all that conversant with the controls.

I cannot see anything likely to be wrong with the UFH pipes if they were designed properly.

Presumably they have all been paid off now and that may leave you in the no-man's land.

You might end up having to get an independent expert/consultant to diagnose the problem and then try to get his costs recovered ( by court action ) against the ASHP installer.

Tony Glazier

 

[LB13]

Thanks for replying Tony.

The ASHP seems to be working ok, in that it supplies plenty of hot water, it just isn't supplying hot water to the UFH - obviously I'm no expert, but I don't understand why one aspect is working and the other isn't, that's why I thought/think it's the Heatmiser that's the problem.

I'm still under guarantee as far as the ASHP system is concerned, but they've sent engineers out twice now & it's still not working.

How/where can I find an independent expert to check the system? I can't find anyone to come & diagnose the problem, which is why I'm posting here! Everyone I contact says they've no experience of UFH with ASHP... seems I'm a trail blazer as far as this is concerned

 

[Agile]

UFH is the only way to get good performance with an ASHP.

If you wanted to take a video of all parts and control settings and post it then perhaps someone here could identify the problem.

Tony

 

[Boilerman2]

I assume you realise that ASHP systems need to operate 24/7 ?

 

[dcawkwell]

I think it sounds like a controls problem.
You should be able to set the heating to 24 hours a day and turn all the thermostats right up.
Set that and see if the underfloor begins to heat up.
It may take a full day for underfloor heating to get going.

A competent heating engineer should be able to fault find the system
and have it up and running.

You need to call someone else out and tell them to get it work.
You will have to pay for this.

It is unlikely you will get any joy from a builder or the air source heat pump engineers. Do it now before it starts getting cold or you will have to wait for a time when an engineer is free.

Always get someone who can do the whole job not separate people for each bit.

 

[LB13]

Problem has been identified and solved - there was no water flow through the manifold due to air in the underfloor heating pipes

The ASHP side was working perfectly, but it recognised there was no return flow when the manifold called for hot water, and automatically switched off.

A power-flush of the pipes cleared out all the air, and everything is working fine now... thank heavens