Single pump for ASHP UFH and Radiators?

[Navron]

So, our house has recently been built and it has a large floor area of about 400sqm. Downstairs is all wet UFH and upstairs has radiators. These are running from 2 x Clivet ASHPs, but I noticed there is only one single Grundfos MAGNA1 pump servicing all the radiators and all the UFH. This has a proportional pressure mode for radiator systems, a constant pressure mode for UFH and a constant speed mode for "constant flow applications" (this is what the installers set it to).

The controller is a "homely" one, which has a single wireless thermometer in the downstairs of the house.

With the heating going on recently, the upstairs is always noticeably colder than the downstairs. All of the lockshields and valves are wide open on the radiators. Likewise the UFH manifolds have everything wide open.

There is a constant rushing water sound from the radiator pipes when the heating is on. This is directly proportional to whatever flow speed I set on the single pump. When I am in a downstairs room in the house, the measured sound level difference is about 10db between the pump being on and off - that's not the pump sound, it's the sound of the water rushing through the pipes.

I have a feeling that the entire system has been set up incorrectly with cheap accessories. E.g. the UFH manifolds have no automated controls on them at all, just cheap plastic caps placed on the valves but not tightened at all. Flow temp for radiators and UFH seems to be always about 25c.

 

So there is a bit more info there but the basic question is should both UFH and radiators be running off the same pump?

 

 

[JohnMo]

Sounds like it's all been installed but not really commissioned.

 

Why two heat pumps?

 

Are you running through a buffer or low loss header or are the heat pumps connected directly to the UFH and radiators?

[Conor]

What design and heatloss calculations were done? Do you have a table showing required for rates fro each zone? If it was designed for a 30c flow temp and it's set to 25c, your house will never be warm. Oh, and nothing wrong not zoning individual UFH loops, in fact better as a single zone. All three of my manifolds are set like that, I run the house as two zones and it's perfect.

[Navron]

1 hour ago, JohnMo said:

Sounds like it's all been installed but not really commissioned.

 

Why two heat pumps?

 

Are you running through a buffer or low loss header or are the heat pumps connected directly to the UFH and radiators?

There are two ASHPs because (I was told), that the heat loss calcs that were done could not take into account the MVHR, in order to be eligible for the BUS grant. Apparently one ASHP would have been sufficient but then I wouldn't get the BUS grant.

We have a CH buffer tank and a CH expansion tank. For HW there is a 300l cylinder and an expansion tank.

[Navron]

1 hour ago, Conor said:

What design and heatloss calculations were done? Do you have a table showing required for rates fro each zone? If it was designed for a 30c flow temp and it's set to 25c, your house will never be warm. Oh, and nothing wrong not zoning individual UFH loops, in fact better as a single zone. All three of my manifolds are set like that, I run the house as two zones and it's perfect.

It was all allegedly commissioned a couple of weeks ago. There is also an MVHR system and I suspect the focus was more on that than the heating.

Yes, we've got heat loss calculations for each of the rooms, both upstairs and downstairs, so the radiators have been specified to meet the requirements down to an ambient temperature of -2c. Perhaps it is the case that the chosen radiators meet the requirements so precisely that all of the lockshields and valves can be left wide open.

There are 20 UFH loops, all plumbed in parallel with the valves wide open. I believe they laid the loops in a way to account for the different rates for each zone.