Navron

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.

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.

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?

Thanks for all your help people. We ran some insulated pipes below ground for hot and cold water, taking a feed off the kitchen. There will be a bit of a wait for hot water, but that's far preferable to a separate water heating system in the garden office. Sadly it was too late to get the UFH extended out into the garden office as that had all been completed, but had I known in advance I certainly would have done that too!

We have a house and garden office build currently in progress. The garden office is 8m x 3.5m inside and is only a couple of metres from the corner of the kitchen. It is multipurpose so is both for use as an office and will also have a sofa bed and small bathroom with shower for occasional guests. The plumbers are saying it would be too complicated to get a hot water feed from the UVC to the garden office for the shower we have planned for that room. They said the run is too long, the pipe may freeze in the winter, the hot water may not be hot enough and we would have to wait too long for hot water. They have no concerns with putting a cold water feed in a trench from the house to the garden office. The position of the buildings is such that the hot water feed into the kitchen is about 13m in a direct line to the furthest corner of the garden office, then another 3m inside the garden office to the shower location. The bathroom will not be used very often for showers - maybe two weeks per year at the most. We are having trenches dug soon in any case for the waste pipe, electric, ethernet, and cold water supply for the garden office. My uneducated opinion is that maybe a pre-insulated hot water pipe could work fine in this scenario, given we can accept quite a long wait before the hot water starts flowing, but the plumbers are suggesting either an electric shower or an under-sink water heater, either of which would require us to upgrade the electrics quite a bit (being 30m from the consumer unit). Has anyone faced a similar challenge and/or what are your recommendations or comments?

Thank you. I think I have described the construction incorrectly. It is actually like this: some walls are wet plastered but the majority will have a make-up that is brick, insulation, block, plasterboard and then a skim coat. So for those walls that are plasterboard with a skim coat on top, will I need to tape up all the plasterboard joins and also tape the plasterboard to the floors and ceilings?

We are currently quite far through a build - brick and block construction with stud partitions upstairs, then all plasterboarded and wet plastered. Flooring upstairs is Kaberdeck that's all been glued together with expanding foam. We have the MVHR going in in a couple of weeks and I'm wondering about taping up all the joins between plasterboards. By my rough calculations I would need thousands of pounds of tape to cover all the board upstairs and downstairs. We will be taping all the windows, but is it necessary to tape every single plasterboard join? Note we have 2.9m ceilings downstairs and vaulted ceilings upstairs that go from 2.2m to 3.2m and about 390sqm total, so it's a lot of tape we would need. Is there a cheap tape that can be plastered over or some other way of achieving adequate air tightness? Note we are mostly doing MVHR for the mechanical ventilation bit and only secondarily for the heat recovery bit.

Thank you, I've done the calculations and I get the following output: Largest Total heat loss power (W) is 8627 (for 30c delta) Largest Total daily heat loss power for average OAT (W) is 4641 Largest Total daily heat loss power for minimum OAT (W) is 5441 The MCS engineer said he based his calculations on no MVHR, because he is not allowed to take it into account, so if I set MVHR efficiency to 0% I get 12639, 6727 and 7985 for those figures. I have kept Outside air temp at -10, Room temperature at 20 and Under slab soil temp at 8 These figures all look a lot less than 22,000 kWh....

Hello, We are building a new(ish) house in the SE - the existing building was mostly demolished but foundations and some walls remained and are being reused as they were post-1986 so fairly decent: insulation under slab and insulated brick and block cavity walls. This is all being built to meet or exceed pre-June 2022 building regs, due to the date of the planning application. This is not a passivhaus but will feature MVHR and ASHP CH and UFH to GF with radiators above. The house is fairly large at 378sqm overall, with 5 bedrooms. 2850mm ceiling height to the GF and vaulted ceilings to the 1F with 2150mm to 3200mm ceiling height. We are having toilet cisterns plumbed in independently of the rest of the CW pipes for a potential future water harvesting effort. The thing that has really surprised me is the MCS engineer's heat loss report: Energy required to heat property: 42,552 kWh Energy required for hot water: 6,550 kWh Flow temperature: 50c MCS SCOP Heating: 3.67 MCS SCOP Hot Water: 1.75 He says we need 2 x Mitsubishi Ecodan VAA 11.2kW R32 ASHPs. I did my own rough Ventilation and Fabric heat loss calcs and mine came out 30%-60% lower. Also I asked another installer to take a look (at the (seemingly high), heat loss calcs and he said a 16kW ASHP would be sufficient. This seems like it's pretty over-specced. What do you think?