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I've been told if the incoming supply is insufficient for the uprated fuse, the supply upgrade is free. But if you ask for a new service, or moving the meter, that counts as chargeable (presumably seen as discretionary).

After I applied for the upgrade, their crew came round to look at the supply and decided it was insufficient for 100A. Apparently they'll often replace the fuse at that first visit if it's all suitable. Then they booked it in as requiring a supply upgrade, which the crew, and then the team on the phone in a follow-up call, told me was non-chargeable. Next step is a surveyor comes out to plan the supply upgrade, to include closing the pavement, closing the road if needed (not in our case). I have another surveyor coming to look at the property to quote for a plan a three phase upgrade. Presumably doing exactly the same task?

Agreed, could be worse, but I'm not quibbling with the cost of the work Instead that they will be doing the vast majority of the work anyway, and for free given that we require a supply upgrade. But asking for three phase, why can't I pay a fair rate for the extra material and the labour above that. It's like winning a free holiday, asking to pay to add inclusive drinks, and being told if you do you have to pay for the whole holiday. Except that I've not won a free holiday, it is policy to provide the benefit (I realise probably from everyone's standing charges, and am grateful for that).

We're in a 1905 mid-terrace with the original supply cable from the street. With an ASHP, EV charger, 1 or two inverters and batteries, induction hob and 2x ovens going in, we needed to upgrade from 60A to 100A. Our supply cable was insufficient for 100A so we're booked in for a single phase supply upgrade which would be completely free. We'll make use of time of use tariff. We'd benefit from a 22kW car charger. Doing shift work I have abnormal consumption schedules so our diversity doesn't reliably drop the total load much. As a result we could easily hit 35KVA and up to 53KVA. We can make do without 3 phase, but we'd definitely benefit from it. I understand Western Power networks install 3 phase by default if a supply upgrade is required. So I contacted our DNO UKPN to enquire about 3 phase supply. They tell me a 3 phase upgrade would make all works chargeable, estimated at £6700 (inc. VAT) excluding digging on our property. £370 of that is the 3 phase cable and ducting, and the remaining £6300 is the labour (i.e. digging the pavement 3m from the house on our side of the road and making the connection, most of which would presumably be identical to the single phase work). That's prohibitive. I wasn't expecting to get it as good as under Western Power , but I'd really hoped I could pay just the marginal cost of the 3 phase equipment and connection work- it feels absurd to have to pay for the digging. Are there any strategy documents or consumer rights I can quote to try and just pay that marginal cost? Any advice greatly appreciated.

4 years on... Finally have planning and hope to build this autumn. The plan is still to sit the MVHR I'm the eaves. We'll use ended joists to convert the loft and run ducts through those.

Resurrecting an old thread... this is copied from the PAUL guide referenced. The internal RH of the summer daytime normal heat exchange is 74%. The internal RH of the enthalpy setup is 60%. So I'm not sure it's a like for like comparison? Also wondering if the enthalpy exchanger would help with dehumidification if the house is being cooled in summer?

Great thread I'm a little late to. If trenching anyway, wouldn't it make sense to duct refrigerant lines through solid pipe e.g. 110mm soil pipe, and insulate around the soil pipe e.g. with a combination of XPS and spray foam? That would allow changing out the lines if needed, and minimise losses. I presume the air held in the soil pipe would be static and a reasonable insulator. I wonder if pre-insulated refrigerant lines could be run through the soil pipe, and if that would make much difference vs just insulating outside the soil pipe.

https://mhclgmedia.blog.gov.uk/2024/11/21/warm-homes-plan-and-heat-pumps/ Great news, the 1m from a boundary requirement for PD is to be scrapped. In worse news we didn't know this when we submitted our planning application in Dec 2024, to include a heat pump down the garden and by the boundary (mid- terrace). So we've now poked the planning and noise assessment bear. Any idea when this will actually come into force? I can only see references to early 2025.

I realise this is the wrong time of year to ask...but what have people's experiences been of cooling at temperatures above the dew point? This will surely increase humidity, and actually get below the dew point in a controlled manner would be beneficial for the humidity. Was there any need to run a separate dehumidifier? If you had MVHR, what settings did you have to mitigate this? We would have upstairs UFH in P5 chipboard, so moisture control is critical, downstairs TBC. I feel like I might end up 2 loops with the option to set them at different flow temperatures: (Loop 1) UFH and (Loop 2) insulated pipework with FCUs. I have a decent Home Assistant automation setup and independent control of each would be really useful. Running both loops at the same temperature would allow a minimised flow temp and maximised COP. If we want a rapid warmup we can run the FCUs at a higher temp than the UFH. If we want a rapid cool down we can run the FCUs lower than the UFH. To dehumidify when cooling we can drop the FCU temperatures below dewpoint and/or increase their fan speed. We could even increase the UFH flow temperature accordingly to prevent overcooling. This does beg the question of why not purely fan coil units. It's not a gigantic property (160sqm after extension). We'll be fitting new flooring to much of it anyway e.g. for the kitchen & bathrooms I think there's a clear benefit to UFH above FCUs.

Do you then have two loops, one for the fan coil+buffer and one for the UFH? How do you control this? The Panasonic (I think) heat pumps allow two zones at different temperatures. I wondered if there was an easier way of achieving this with other models.

I can see that if you bring in warm air into the cool house the relative humidity will increase- so in this instance reducing airflow through an MVHR would be beneficial. They may reduce a little of the incoming air's moisture as it is cooled by exhaust air but I doubt I huge amount. Perhaps the main pitch for the comfopost should instead be for dehumidification as part of a larger cooling setup.

I'd see the ability from fancoils added to UFH to preferentially cool certain rooms (e.g bedrooms) handy. Without UFH too, I'd go below the dew point using insulated pipe and condensate drains. With the UFH, taking the fan coils below dew point would I think require two loops, a diverter, and a volumiser for the fan coils loop? Unless you can run one coming loop at 7 degrees C supplied in insulated pipe, then blend the UFH to a temperature above dew point? I can see the argument for just adding AC, but as additional outdoor unit wouldn't suit our property (mid-terrace).

So all of this has confirmed for me that a comfopost isn't worth it for us. If you're running fancoils on the same loop as UFH, presumably that gives plenty of circulating volume. It would then run offset above the dew point, accepting achieving less than maximal cooling/heating output from the fan coils. It seems to me there's little point in running insulated pipe to supply the fan coils? And is there any need then to provide a condensate drain for the fan coils?

I initially thought 3 fan speeds seems a little basic, however the panasonic FCUs are only 4 speed https://www.bpcventilation.com/panasonic-fan-coil-unit

is the summer house also UFH? How do you take the water loop from your house to the summer house, and how far is it?

Thanks Dan, your comments on that other thread I linked were very helpful. My understanding is that if you have active cooling, the MVHR should cool intake air using exhaust air if you disable the summer bypass? Are there any benefits you can see you the comfopost additional to fancoils +/or UFH at all? I.e. if money were no object (unfortunately not the case) then could you argue for both comfopost plus the UFH/fancoils?

Hi John, what's the floor area and the floor construction inc covering your UFH is in? Was this ground floor only, or upper floors? That's superb efficiency and personally I'd see the money as well-spent to maintain a comfortable temperature. I still come across lots of people who happily burn oil to heat their house to 25 degrees but think it's unacceptably wasteful to apply cooling using (renewable or even self-generated) electricity.

Yeah I had looked at the datasheets- the largest comfopost can do 2.8kw cooling (ERV MVHR) with 600m^3/hr air flow. So noisy and limited cooling- but I think it's useful to get actual experience of that too. There's another useful thread on here from someone who decided against heat battery/cooling in the end.

Exactly the clear answer I needed! Out of interest though, have you got any data through HA about it? What size heat battery have you got, and what flow temp and air flow were you using?

I forgot to include the link to the product I was referring to- these are what I spotted https://aerfor.com/en/reverso

I've also spotted these recently. I don't love the look personally but appreciate the price and flexible mounting options. I presume these would also give the option for some individual room control of cooling (for examples different preferences for bedroom temperature), although with the small buffer volume issue that's been already mentioned. It also strikes me that the optimal positioning and airflow direction does vary between heating and cooling applications, but I don't know how much difference that would actually make.

Dave, how has the heat/cool battery attached to the MVHR performed over the summer?

Hi all, I came across this post on another forum about reducing the cold bridging across sash boxes. I wanted to see if there was any experience on here. https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16668 I am refurbing my old sash windows in a 1905 mid-terrace. The main plan is retrofitting vacuum insulated glazing, draft stripping, and replacing the mastic joints. We'll be adding internal wall insulation, either Thermactive plaster or PIR, with a plan to boost ventilation (MVHR) for moisture control within a major refurb. We have a single storey bay window with 3 sashes in. I was putting expanding foam behind the mastic where the joint was large, and it seemed to be an endless void. Turns out the boxes aren't complete and are open to the stone on the external face. This is a big cold bridge, with only 20mm window frame and ~100mm stone between inside and out. Obviously foam in here could bust out the boxes and would definitely stop the weights running. I was wondering however about sheathing the weights in plastic pipe e.g. 40mm waste pipe, and filling the remaining cavity with loose fill insulation. Any experience with this/recommendations/cautions?

Thanks Dave, this is fantastic to see and very interesting. What period is that cooling accumulated consumption over? Or do you have a measure for how much heat you've been able to extract over a day? And could you share your approx. floor space? Do you have data for your dew point in the summer? I presume when it's hotter, with incoming air being cooled as it passes through the MVHR, you'll have a high relative humidity and a higher dew point, so the flow temp to the underfloor heating will have to be substantially higher than the 13.3+2 celsius dew point offset above?

Amazing. This is the essentially setup I want to go for. Loads of questions! How much cooling performance do you get? How much additional cooling do you expect from the MVHR? Any buffer in that system, or is there enough volume already? What kind of flow temps are you typically running at with the dewpoint offset? I wonder how much cooler you could run water to the fancoils (using insulated/vapour barrier pipe) if it weren't for the UFH, and the difference in cooling performance? I believe the Panasonic ASHP can do two sides at different temperatures, so wondered about having loop A with a dewpoint offset for the UFH and then loop B at 7 degrees for the fancoils and MVHR