Rodge

Thanks for the thoughts. I'll have a look at the panels and profiles offering, but may well turn to the aluminium route, perhaps with lead to create the specialist joins. Very helpful, Rodge

Russell Griffiths, Thanks for the responses. Re expansion, have I calculated wrongly? - must have done if that is the experience. Doing the calculations with the Coefficient of Linear Expansion of lead and for a 25 degree temperature change gives an expansion of 1.1mm over 1500mm, and 4.4mm over 6000. With the lead only attached at one end, quite narrow (300mm or so) and free to move over its length, I was assuming that the expansion wouldn't be problematic. Rodge

I'm exploring the use of lead to construct in-board/hidden guttering on my small single-storey self-build, quasi Passive. No eaves. I'm wonderng whether anyone has experience of using lead contrary to the specifications of (e.g.) Calder and Associated Lead. These specify a maximum run of 1500mm (most frequently) for a single sheet of lead. But I am thinking of running it for 4000mm strips, simply U-shaped and fixed only at one end to allow for expansion movement. No horizontal joins given challenges in lead Is this foolish? BACKGROUND: The gutter will run along the side of the building, with the water flow running from the upper level, down a 1.1m slope at 31 degrees, to the lower level. The image hopefully gives an idea of situation, and shows the temporary gutter sitting outside the face of the insulation, in a relatively conventional way - just to keep the water off this side to which the slightly-sloping roof drains. This was a trial and my 'eye' doesn't like the look of it on a modern style house. When the roof insulation is installed, the plan is to leave the second layer insulation board 100mm short of the edge, and to 'simply' rest the gutter on that ledge, suitably secured. A major attraction of using lead is the ease with which I could (I think) join the horizontal lead to the 31 degree slope (with a slight bend downward, directing water down the slope) and to fashion an outlet that directs the water horizontally to the downpipe (with an appropriate step down from the horizontal gutter - although the standard 50mm drop down would be require a larger-than-desirable cut down into the insulation.) Grateful for any thoughts. Rodge

Interesting responses, thanks! Sounds very similar to this newer Joule ModulAir product, and if it's quiet, a real contender. But you used the past tense, I guess that's only because you sold the property and moved on? I'm not sure I've got my head around the idea of 'stealing' heat - perhaps it is that the heat extracted by the EAHP from the exhaust stream would have largely been retained by a MHVR unit anyway, and with this EAHP, the incoming air (brought in from outside) then has to be re-heated. The only gain in using this HP approach to this pumped ventilation would be if the EAHP was powerful enough to go beyond that heat transfer ,to extract even more heat from the exhaust stream - to use to both heat up the incoming air (back to the exhaust temperature) and have enough to warm the air (if needed) and provide some for DHW heating. So if exhaust were 18° and external air 3°, say, that would be demanding. I don't see any information in Kelvin's post that this is acheived by this model Plus - and this is perhaps my main concern with combining the HP with MVHR in one unit - there may well be a conflict between the air flow rates to achieve adequate ventilation (normally via MVHR) and fair low rates to harvest, as it were, enough heat for both space heating and DHW. (Although the Genvex seems to do it successfully) So I share Iceverge's notion that 'combining stuff is a bad job.' I'm researching Iceverge's three pronged approach of (1) Immersion and PV divert for DHW. (2) A2A for space heating (3) Stand alone MVHR. A further diagram of system, for clarity Appreciate the input - very inspiring! Rodge

Does anyone have experience of, or opinions about, Joule's new (in 2022) product, Modulair All-E, with GreenComfort and cylinder? It is an Exhaust Air Heat Pump supplying DWC and space heating, both via hot water to radiators and heating of air drawn into the building (with the 'Green Comfort' optional extra). So it combines DWC, space heating and MVHR in one unit - with a cost of around £7500. The target market seems to be primarily flats less than, say, 100m2. Source: https://joule.ie/modulair-all-e-product-page/ I'm aware of strong reservations on this forum (by Jeremy Harris, in particular - sad that he seems to be no longer contributing) about Exhaust AHP but this product seems to avoid the substance of those reservations since it draws external air into the building through ducting, along the lines of MVHR. As a self-builder of an almost Passive House, 77m2 on one level and almost open-plan, I'm attracted by the notion of killing three birds with one stone (DHW, space heating and ventilation). Modelling of plans by Warm consultants in Plymouth suggests a small heat load on cold days of 24Kwh over 24 hours. My main concern is around noise - the data supplied are thin and not convincing. And in the winter, the EAHP will have to circulate the greatest volume of air to extract the required heat input - the noise of which would be much less noticeable if it were an externally-sited ASHP. Any thoughts, much appreciated. Rodge