BadgerBadger

Does anyone know is Ecodan's have an integral circulation pump, or do they rely on an external pump in the system to move water through? I'd found the min/max flow rates in the manual (8.5kW Ecodan, ~11l/s to ~24l/min) so had assumed they did. But struggling to find any more information on pressure/pump curves etc. so doubting my assumptions, and wondering if its the flow rate requirements to be matched with an external pump?

I only meant skewed by that our "downstairs only" UFH area is more than half the floor of the house. Not envisaging any trouble and will simply adjust the flow rates accordingly to account for different losses, but if we did end up zoning anything this vaulted space would be the obvious candidate as it's quite thermally separate from the rest.

With a bit of improvement in routing/manifold position we can save a couple of loops (about to start my LoopCAD trial) but really there's so many because I arbitrarily picked 150mm centres! This was purely on the basis of "it will let me run a lower flow temp, and therefore that must be better" but this is really what I want to work through and see if it's actually the case. If that choice stops me using the heat pump directly, then I'll likely end up with a more efficient system by increasing the centres. More reading to do I think! The heatpump sizing, and to an extent the spacing, is also mitigating things if I've got my sums wrong and the house doesn't perform as well in practice. Plus faster re-heat times on the DHW with the more powerful pump.

Thanks Jenki - Ground floor UFH area is approx. 160m2, with total house of 260m2. Bit skewed as we have a large single-storey volume! The routing to reach the plant room isn't very efficient, so am trying to improve that.

I'm trying to finalise our UFH and ASHP strategy ready to start buying bits and getting it installed. But keep going round in circles... Background is we have a large but well-insulated house with usual MVHR etc. My heat loss modelling is showing losses of 170W/K, giving a total heating demand of 4000W at -3C. We're planning UFH in screed on the ground floor, with no heating upstairs. Planning on an 8.5kW Ecodan ASHP. Had some UFH designs back and we're looking at about 15 loops. Trying to get away from zoning, but this might be another leap of faith for my wife. Things seem to have the potential to get complicated very quickly! With buffers, two manifolds, extra pumps etc, but I get the feeling much of it is specified to cover all bases without a true understanding of what is actually needed. I'm really keen to keep things as simple as possible. I came across this article which highlights how hugely dependent the final COP was on system was setup, and examples with buffers etc. are significantly worse. https://renewableheatinghub.co.uk/how-to-correctly-install-heat-pumps-so-that-they-work-properly-and-efficiently So, can I go super simple? Put my 15 loops on a single manifold, no buffers and just let the ASHP pumps do all the circulation. I recognise that maybe the ASHP integrated pump can't achieve the same flow rates as external pump (I think the 8.5kW Ecodan can do ~11l/s to ~24l/min) but given we're at very low flow temps maybe that's OK? I guess I'm trying to work out which sums I can do to show if it is/isn't a problem, and likewise justify the inclusion of additional items.

We put the main sewer to boundary inspection chamber connection in right at the start of our build. One of the best things we did, got all the roadside verge work out of the way in one go and I plumbed a temporary toilet into the boundary inspection chamber too which has been brilliant

We ended up with loads from early in our build, as you say it's cheaper to buy and re-sell than hire for anything more than a few days. Once we had them, we've kept them for the duration of our build as they've been absolutely brilliant. Really useful to just throw them down whenever we end up with a muddy patch that's causing us problems. As well as getting vehicles in an out, it helps just keep the site tidy in general as the routes between the site toilet and welfare etc. are all protected. There are lots of different brands, I think ours have TurfMat printed on them but they're practically identical to the EuroMat ones you've linked above. When comparing keep an eye on the thickness, and make sure they're HDPE not LDPE. Note the EuroMats in your link above are 12mm HDPE, whilst cheaper EconoMat is LDPE. Let me know if you need some, I have some we can sell if you're interested.

Does your new build come with a warranty? This is the sort of defect they should have picked up during build. As the warranty could be responsible for claims on future issues I'd definitely involve them on remedial work.

Perfect, thank you! I can handle that I'm sure!

Thanks, I'm tempted to try without - I can always buy a a pre-heater separately to install in the unit if I have issues. Bit worried about over-ventilating our master bedroom and getting very dry air, it's got quite a large floor area so ventilation rate has ended up a bit above passivhaus guidelines for bedrooms with two people but likewise I can always re-adjust rates if we have problems.

Thanks - I think I'm leaning to going with the Q450. I can't quite see any justification for the extra money on the Q600. So now I'm into enthalpy exchangers and pre-heaters! I was very tempted by enthalpy, until I realised the efficiency was ~10% lower than the standard. So how essential is the pre-heater? It seems somewhat power hungry so I'd be a bit worried about it running lots. Does anyone know if the Zehnder units protect themselves if frost is a risk? (i.e. shutting down?) We're down south so not expecting hugely extended periods where frost would be an issue.

We did a similar detail with brick plinths and piers and "recessed" weather boarding. The walls are block - cavity - block as the main buildup, and then an additional skin of non-structural facing brickwork sits Infront of this. The cladding goes onto membrane and battens on the outer blockwork, adjusting the batten depth to give the amount of recess you require. It's an expensive detail as you basically build an lot of additional blockwork, but I think it it really lifts our build.

So we are finally getting stuck into first fix and ready to start MVHR duct work. I've had a few quotes from the usual suspects, and even paid for a preliminary design, but to be honest have been a bit underwhelmed by what I've been getting back. So I've been doing calculations myself and I think I'm getting to a solution. Using a mix of 90mm semi-rigid and some flat/oval semi-rigid to run a service void, and have managed to keep the flow velocities all well under 2 m/s. Ventilated internal floor area is approx. 250m2 so I'm working from a max ventilation rate of 275m3/hr (~75l/s). I've done some sums on the pressure drop of my longest duct run which on paper seems to be about 40 Pa (as I've kept the flow velocity low) but also assuming it may also be somewhat higher. I'm going for a Zehnder ComfoAir unit but some quotes have been based on Q450 and others on the Q600. So am unsure which to go for. Initially I'd assumed the Q600 would be quieter/better as I'd be running it further away from is maximum but the ComfoAir brochure has some handy plots, I've added my operating point and now I'm not so sure! Feels like I'm a long way down the curve on the Q600 already and in reality may reduce ventilation rate further if building regs rate is too high. The Q600 sound power also looks higher at ~45-46dB, instead of ~43-44dB on the Q450. Is that right? What do you think?

We're doing something very similar at the moment with oak direct glazing an entrance. We had some quotes and it was very expensive, but in principle it's quite straightforward, so I think a lot of the expense is the "risk factor" of call backs, poor installation etc. We dug into the details of how to do it and have essentially shouldered the risk ourselves with some help/advice from a local oak framer. We have tightened up the airtightness etc where we can and going for triple glazed units, but also accepting this may not be the most efficient part of build. Hopefully it will absolutely fine but it's not in yet...

We spent a long time going round this circle, and found very few options that matched our expectations (i.e. good quality wood finish with unobtrusive joints). I think there were some "designer" timber options from Norrsken that looked good but were very expensive. In the end we concluded for most suppliers the timber was simply not designed to be on show, so we went painted finish with a view to bringing in the timber-look elsewhere in the final decor using the large amount of money we'd saved!!