Benpointer

Both the MVHR units we have had in the past had automatic summer bypass included by default. The issue is "If the indoor air is warmer than the outdoor air..." that's precisely when summer bypass doesn't operate (at least as far as I am aware) because 95% of the time you want to keep that indoor air warmth to cut heating costs.

I'm learning a lot here, thanks all! What happens to the MVHR when you are operating the UFH in cooling mode? Presumably it has to still run, to remove the excess humidity. Does it switch to summer bypass? And would it in fact be better if it didn't, if the air outside is hotter than the air inside, it would be quite nice to exchange that heat from the intake to the exhaust. Too many questions buzzing round my brain!

Am I right in thinking that a fan coil will have its own condensation collection and therefore require a drain connection? Also, that a fan relies on an external feed of hot or cold water to do its work - so it's effectively a radiator* with a fan? (* I use the term 'radiator' in the CH heating sense.)

Apols all, I know this is a huge thread but... what was the answer to the original question "Which ASHP are set up to cool"? Also, do they all only cool through the UFH loops or can they run cooled water through fan coil unit with condensation collection? I am worried that a cold floor on a hot humid day will just cause condensation all across the floor. Apols for the dumb question - trying to understand if I need to specify a separate aircon system or I can get the ASHP to do that for me in our new-build for which we are at the early design stage .

Pah! that's taking the easy route. You should put the pipe it goes into on the lathe and cut a female thread in it 😜

The oil-fired hot water system radiators in the house we are currently renting are heating air which rapidly radiates half its heat out through the windows conveniently placed directly above the rads. Why do people do that?

That's a great explanation Steamy, but I must take issue with one point: "So while we like to think of thermal energy transfer as conduction, convection and radiation, it is really all radiation." Convection is surely a bit different because that is primarily the movement of material rather than heat.

No worries - take it from me, living in the Blackmore Vale addles your brain 😉

"Dorset Council does not operate CIL in the former North Dorset area and mitigation required to support the needs of new development is secured through section 106 legal agreements. " https://www.dorsetcouncil.gov.uk/w/dorset-council-community-infrastructure-levy Edit: Could your plot be just outside the old North Dorset District Council area?

Good point but fortunately there's no CIL in North Dorset.

Yes, it's 1.5m distant at the closest point. Presumably though if the original rotted, I'd be allowed to repair it like for like (or perhaps WRC for pine)?

Some pics: 'Classroom' on left, TPO'd oak behind, garage on right. Extract from topo survey, 'classroom' shown as 'STORE',

Apologies for this I will try to be brief: Our plot has full PP for a 160m2 3-bed chalet - not started. The plot also has two existing buildings on: 1) A 9m x 5m timber frame 'classroom' - was used for dog (owner) training - pitched felt roof, eaves 2.8m, ridge 3.9m. 2) A 6m x 6m timber framed garage, pitched felt roof, eaves 2.3m ridge 3.9m The current PP shows those two buildings but makes no other reference to them - importantly they don't have to come down as part of the PP. We are going to submit revised PP for the house because we want single-storey - we do not plan to propose any changes to the two existing buildings. The 'classroom' is within the canopy (and no doubt root protection area) of a neighbour's oak which now has a TPO. I doubt we'd be allowed to knock the 'classroom' down and rebuild in that area because of the oak tree. I want to repurpose the 'classroom' as a workshop, ideally before our house build but potentially afterwards. So my question is: what can we do to the classroom without obtaining PP (and ideally BC)? E.g.: Reclad it? (It's currently clad in ropey, rotten, softwood T&G.) Repair the frame where needed? (There's bound to be some rot here and there). Insulate it? (It's lined with plasterboard inside - not sure if there is any existing insulation.) Replace the roof with an insulated, tiled roof? Replace the wooden floor with an insulated, concrete or screeded floor? New windows? Basically, I am happy to keep a building on the same footprint because we'd never be able to use that part of the plot for building due to the TPO'd oak. But ideally, we'd put a more substantial, better-insulted, better-built building on the same footings. Any thoughts? Thanks!

Getting a coper pipe vertical? Do it by eye, shirley?

Reinforced concrete ring beam* on top of the slab in place of the 2 courses of brick sounds good to me. (But I am not an engineer.) (*Well, u-shaped beam as I assume you'll want to drive in without going over the bean on the door opening.)

Indeed. When referring to a person unknown most people would opt for 'they' rather 'he or she', as in: "someone called but left no message - I don't know what they wanted". No one would think 'they' referred to a plural number of people in that sentence.

We could hardly hear ours. Very quiet, almost silent.

Interesting discussion. We are considering using local greensand stone walling for some sections of outer skin on our TF or SIPS build. The Housebuilder's Bible prices stone at £245 per m2 versus £80 to £100 for brickwork, render, or cedar, which we also plan to use. So, stone would be 2-3 times as expensive according to HB. Is Mark Brinkley wrong on that?

I've spoke to our architect, he thinks we will be fine as we don't plan to build close to the tree but we will need an Arboricultural Impacts Assessment to demonstrate that we are taking account of the TPO. Power was put in last year - across the tree roots, I would guess - by the vendor and before the TPO was in place, so all good there. We have two existing buildings (a garage & a workshop) within 10m of the tree and we had considered knocking those down and replacing them but now I feel we can refurb them without any digging. Thanks as ever for the feedback / suggestions.

Thanks. There are no other trees within 50m of where we want to build. The oak in question is on our neighbour's plot. Our topographic shows it to have a 700mm trunk (I assume the surveyor can measure that accurately from a distance these days). The canopy (c. 11m dia) extends over our property by a few metres but not where we need to build - we should be able to build >15m away from the centre of the oak.

Yes, well, I am now worrying how close that oak tree is to our proposed build (plans not submitted). How far does a TPO extend?

Just noticed that the plot next to ours, which submitted full plans in early October, has has a TPO slapped on an oak tree on the plot in November and the Tree Officer has now complained the self-builders didn't take account of that in their (earlier) planning submission (!)

Brilliant! Thanks Alan. (Should be a pinned thread maybe?)

Chris, can I ask what you use as a trigger warning when you look companies up on Companies House? I assume it's not going to mark them up as 'about to go bust', nor give much indication that they have major cash-flow or credit issues?

John, I am intrigued by your suggested approach. Our last house (60s bungalow eco-refurb) had ASHP + UFH + MVHR and it worked really well. We had 6 zones. Most set to 21C but the main bedroom was set cooler (18) and our en-suite bathroom was warmer at 23C. Because we like it that way. We are now embarking on a new self-build. Early days yet but we will be aiming for near-Passivhaus levels of insulation and air-tightness. But: we want the bedrooms cooler than the living areas, and we want the bathrooms warmer. So I am thinking at least three zones, probably 6 to 8. I certainly don't want to be p*ssing around with balancing the flow rates to each UFH loop to set differential heating in various rooms. That sounds like madness when I could simply use a room thermostat. What am I missing?