ruggers

Following this because ive just been looking at the same thing. Current house has attached garage with timber fire door and the garage door is 40mm insulation sectional but not great airtightness around the edges. The timber door to the house i feel is a weakness too despite a 4 sided seal. Looking to start an airtight build with the same internal garage set up id like a good door between house and unheated garage. Drop seals might help routed into the underside, but I'm hopijg theres a rebated upvc fire rated door available for a good seal.

Seems so. Maybe concerned where we live is too cold or just not heard of them. I was about to say, It's nearly always 3 degrees or less in a Scottish winter so it would be leaking out constantly. So it's just if the pump has no power to it. If it's not running because theres no heat demand but it then drops down to a low temperature, it would fire the pump up instead of dumping the pressure.

Thanks John, What have you got installed in Scotland. We have freeze issues outside up North. If you just used the anto freeze valves, would you not just lose all of the system water every time it's below 3°C outside, is it not like a combi where below a certain pressure the system stops working until you fill it back up?

What brand is the 25L buffer? I've no idea why they wanted to use glycol then, especially as a registered installer. You'd expect a random plumber to maybe do things that way. I wouldn't fancy glycol throughout the whole system sounds very messy if you need to drain down or if you got a leak, plus it won't be cheap like water is. Why does glycol lose efficiency. Filling the whole system including radiators would mean even less efficient?

I can't see any difference in them two senso comforts but there must be if they're on the same site at such a price difference. Them UFH manifold pump sets with the TRV style mixer are just for on off controls and don't work very well with weather comp. I could probably get away with only one mixer for the UFH and let the radiators demand the highest temperature which they usually do, but some people have rare instances where the UFH demands more than the radiator circuit. I just looked at Vaillant because they get rated highly like eco dans. Boilers I was looking at the Viessmann system boilers for their low modulation. Much cheaper than heat pumps to install. How does the water not freeze in the outside pipes? Why's the Vaillant installer saying it has to have glycol between the compressor unit and whatever it connect to indoors? I'm not up to speed on the terminology of it all. Outdoor unit is the compressor? Whats the monoblock? If the hex unit is the internal heat exchanger between the indoor piping and the outdoor unit, if you don't use one, hows it all connect

@HughF Well I plan to have have radiators and 2 towel rails upstairs ran off their own manifold in 15 or 16mm mlc, ground floor 85m2 of UFH all on weather comp. My rough price guide i added up was based on what I'd picked up from brief reading only. Theres other parts I know I'd need but don't know the names or prices of them having never installed an unvented cylinder. With a gas boiler I would install 2 mixed pump sets to independently control the curves. 7Kw ASHP £3832.20 inc vat. Heat pump warehouse. - 5Kw cheaper again. 250L UniStor £1208 inc vat. Hex module £698 inc vat. 25L Expansion vessel £60? Senso comfort - One for each floor? £200 each or 400 each? Will post link at end. 45L buffer tank £560 - This was Vaillant, could be other brand & could be smaller? Underground pipes outside £400 for 4m? Uponor do one in insulation. Flamco Meiflow x 2 mixed pump sets £300 each Electric control box to connect boiler to the mixer valves - £225 each for other boiler brands - Would need 2 Mag filter £75 Lagging - decent type £50 Rotary isolator switch - Better looking black one £50 Armoured cable from consumer unit to ASHP £25 Glycol £? Pipework & press fittings for plant room £500? Press fit tool hire £60 Pump & temperature sensor for buffer £100? Anti freezing valves £200 for 2? Various valves for internal plant room £150? Total £9100 inc VAT - £7300 excluding VAT (1800 VAT reclaim). Whats the difference with these? Why is this £835 for 2, https://www.plumbnation.co.uk/site/vaillant-sensocomfort-wired-pack-2/?fbclid=IwAR0EHaN2sOacqh48JkiexIlu2FueI1lXNCqVRxuQDlPhYNyGgt4V6BvapjY And this is VRC 720 is £195 each. https://www.plumbnation.co.uk/site/vaillant-sensocomfort-vrc-720-weather-compensating-room-thermostat/?fbclid=IwAR2BEGi0orMwCoxM1y-dHu1KyhTJb3XprGW_MnZFdIxlLlFkaJhl8eMkPvM

I think if I was to buy Vaillant it would cost me £8750-9000 for components only no labour. I can only guess some prices. Its about 3-4k more than a gas boiler set up. The annual savings would take 15 years to recoup with the more expensive services factored in to keep a warranty unless it was all self install. I've tried calling Vaillant and Viessmann and Vaillant seem useless, only now and again you get someone who knows what they are talking about in renewables or technical. Basic stuff they can't answer. They don't call back. I don't think the UK knows enough about them yet, not everyone but most. Theres not enough info. available for me to feel confident in an installer or myself fitting one. Everyone Ive spoken to has a different way to do things. Your saying no need for a Hex unit, installers say outdoor unit should come to the indoor hex unit with glycol in then from the hex I can have water in my system. Or you can have a full system of glycol which sounds terrible, especially if you had a leak. Others have said no need for any glycol just water between indoor and outdoor units and some anti freeze valves. Some say try not to use a buffer because it loses efficiency and others say to use one. Is this just to make it easier to hide a half thought out design or they really are needed on most installs?

I don't understand that part saying it's not a bad thing when you need low output. I thought the low output is what causes it to cycle which is never great? I wouldnt need anything too big for a 4.5-6kw heat loss depending on which figure was used. Bigger pump can reheat a bigger cylinder though and quicker. Does the buffer not end up the same as temperature as the system water so then it just cycles again or is it set to take higher heat with it's own stat? How much efficiency do they remove, 45 litres is quite a lot of volume.

What are you running in the outside lines from the compressor to indoors? Whats separating this, theres usually a wall unit isn't there with the heat exchanger in? I've seen the Meiflow jackets housing esbe mixing valves with control units for controlling the heating curves, and grundfos or wilo pump inside. Is that set up for priority hot water with the 3 port valve? The Unistor cylinders have a 15 minute reheat time or 11 mins to 70% for a 250L

I have a plumber friend who's gas safe and G3. He's getting old so not up to speed with weather comp and the latest tech but I've been learning as much as I can. He's happy to work & have me involved. Based on everything gas, which i can get my head around a little easier, I was going to fit a low loss header & two pump sets, one mixed, one unmixed. I'm not sure if you still need the hydronic separation with heat pumps but the hex module indoors separates this. It's just with having radiators first floor and UFH down are they not different flow rates or all the same with a heat pump? Arotherm is just because it generally gets a lot of good reviews and seems popular and their cylinders are really good & a tidy package. Impressive reheat times. It seems easier to learn once you've focussed on one brand. If self installing, is there much difference in using other models? I work it out that a lot of these installs are making £1000 a day for 5 days work instead of £300-£400. Even them prices are a lot. I need to see a drawing for a piped system, it's just all the new terminology for component names. Viessmann has a nice display unit with the heating curves, lots on youtube to see. Struggled to find any on Vaillant, only the senso comfort but it just shows program settings like times and temperatures.

I agree Mike, I'm not concerned about the coldest days of the year, I will have plenty to cover that. Although it doesn't feel like it, the average temperature for my area is 8°C so having a unit that can cope in the extreme cold but also modulates down low in the warmer months enough not to cycle is very important. I run my heating from October to April normally. How can you draw 600w if the lowest modulation is 2.1 or 3kw pending which model is selected? I know that with gas that the lowest modulation is 1900W & this would mean that the boiler would cycle from outside being 10.5°C. I've no idea how to work this out for electric modulation, haven't found anyone who can. 4.5Kw heat loss is 183W per degree of temperature change for my indoor and outside design temps.

@HughF @ProDave I've done my own heat loss survey on heat engineer and spent ages trying all different things, I've got it as accurate as can be from the details I input. I'll be able to shave a little bit more off it, but theres no way anyone coming to do another will spend as much time as I will, they'll just take as close to U-values & air changes where as I've got the exact ones. there should be no reason for someone to do another. MCS seems a farce. If MVHR reduces my heat loss by 25%, then it should be factored in so I require smaller radiators, then if I run it at a lower flow rate to be more efficient, I have room to upsize them to suit. If using my none MVHR heat loss figure, I can't run the flow lower than 40C or the radiators are physically too big for 2 of the rooms. If I'm to fit a heat pump I want to fit an arotherm plus, but I won't get the 7 year warranty if I fit it myself & would need an unvented cylinder. I've done full house combi's but never fit cylinders, expansion vessels & more. If shown I'd learn it easily but theres no source for me to learn it from it would take ages. I think people fitting heat pumps are over charging by thousands, they are no more complex than a gas install for a competent installer.

You can either buy pipe clips that are split lengthways and clip around the pipes, maybe called rad snaps, or buy something like these. https://radiatorvalves4u.co.uk/500-radiator-pipe-shroud-130mm-long-brushed-copper/?gclid=Cj0KCQiAj4ecBhD3ARIsAM4Q_jFK8hVmeIjPzYSJcCcgfNrj4emtMvOcPXF4129rJTGDhiVDEabp9wQaAhctEALw_wcB

@HughF I can't install it, to obtain the 5k grant you need to go through MCS, to get the full warranty you have to be a registered installer and Fgas certified. I can size everything up & I can fit the underfloor, the radiators and piping but not the plant room install or unvented cylinder. All these new regs, Part L and complying with things that require heat loss surveys for weather compensation, and then we don't stick to the figures used from the results.

407mm centres probably won't collapse the house if it's 1220mm sheets. Probably more important to see if it has to be ply or OSB or either.

So Looking at the 7kw and 5kw Arotherm plus to install in a self build not started yet, there's a few things I need to understand related to sizing the pump & heat loss. My heat loss with natural ventilation is 6.2Kw, or 4.6kw with MVHR fitted which will be getting installed. I can improve this slightly and both of these figures include 10% added on for exposed location due to height & coastal area up North. Both Vaillant and the Vaillant local installer have said that when sizing for an ASHP, they have to exclude MVHR from the heat loss survey and base it on natural ventilation as thats the worst case situation of when someone returns from holiday to a house that hasn't had it's heating on and theres no heat for the MVHR to recover. It's quite annoying because using the higher 6.2Kw figure means that I need to size my radiators much bigger, and the physical size of them increases which for my largest bedroom & my main bathroom end up huge. I wanted to lower the flow temperature to get the system running as efficient as possible but going below 42.5°C flow (40 MWT at DT5) is the lowest I can go. having a 40°C flow (37.5 MWT) means that my bathroom radiator has to be 2400w and it would look too big for that room. The heat loss for the bathroom is 559W before a scaling factor is applied. A small reduction in mean water temperature has a huge impact on enlarging the radiator size. If I was able to use my lower house heat loss figure of 4.6Kw, it would allow me to run at a lower flow & return as the heat loss per room is much lower.

Less load. So if a gas boiler has a maximum output of 19Kw and a minimum of 1.9kw, you know that on a warmer day it will be running closer to 1.9Kw and on a cold day like minus 3, it will be running closer to 8Kw for an average house (Maybe higher pending the heat loss) So I wanted to know does an ASHP rated at 7kw run closer to 7kw when outside is freezing, but on warmer days like +10°C, then ASHP would only run at 3Kw. So drawing 3kw of energy when in use as opposed to 7Kw? I don't have one yet, I've been looking at a Vaillant arotherm plus 5 or 7Kw. @Dan FI've managed to get the arotherm performance date from them but it's not east to understand. If i'm looking at the right part, it says a 5Kw unit heat output min/max = 2.1Kw - 6.9Kw For a 7Kw unit its = 3Kw - 7.4Kw

So the Chemical anchors are also for shear strength in vertical loads where as normal masonry screws or screws and plugs could loosen or bend essentially? There would need to be a lot of direct win load and wall movement to move the block work and timber frame though to band screws? The posi webbed joists under each stud wall are designed with noggins so look like a ladder under the 22mm floor decking.

Just reading over this old post, Is it better with ASHP's to have a unit larger than what required, I thought as long as the unit is more than the heat loss your covered if using priority DHW. Do larger units not have a higher minimum modulation so in the warmer months cycle more than a unit closer to the max heat loss? Why does a 7Kw rated heat pump run higher than 7kw when it's warmer outside and theres less load on it? I though the unit rating was their max output and anything warmer than the outside design temperature would mean they run at less Kw. Example: 7Kw unit with 6kw heat loss at -3c would be running almost full capacity, but at +10c, it might run at something like 2.5Kw and a much lower flow temperature if using weather comp. I must be misunderstanding it all.

They don't, lateral support isn't vertical loading. They are stud walls are to be faced with ply to help prevent the upper elevation walls from falling inwards under high winds over time, they are required because my ground floor load bearing walls don't continue up into the first floor. The Joists are supported on the ground floor load bearing walls and the roof trusses support themselves over the span.

It's just what the structural engineers report said, to screw them. Screws are usually bette than nails but much slower. Chemical anchors seems a bit over the top and m10 rawls.

Studs at 400 lateral centres, noggins at 600 vertical centres with the vertical timbers attached to masonry walls every 300mm via chemical anchors. Movement joints & outer leaf expansion joints to line up with key areas of where the stud walls are. Walls ties every 225mm around door and window reveals including the expansion joints.

The 12mm ply face is to be screwed but the studs it doesn't specify so I'd have thought either. It's for lateral stability to the building not vertical support. Fixings to the masonry walls every 300mm vertical centres via M10 resin chemical anchors.

Yeah I'm aware of this, it's a while since I've fit any sheets and will check sizes sure everything 2400x1200 now but some used to be 2440 x 1220mm Your correct, I didn't read the small print on a recent separate structural detail provided by someone else 🤪 It's 400 c/c with 600 vertical noggins including 12mm plyboard.

Is that 600mm for both spacings? 600 for the gaps between each vertical stud and just one horizontal run of noggins through the middle 1.2m up?