ProDave

I think this blog has just served to ask the big question WHY? when it comes to basements. Looking at that huge, deep, wet, fragile hole, that has cost you a lot of work and a lot of muck away, and will cost you more still to finish it and fill it in again, it does not take a genius to work out the cost per square metre of the basement room will be a lot more than the rest of the house.

I am only "not keeping the same temp 24/7" in so far as I turn the heating off overnight as I want a completely silent house at night (I still have an issue with noise from one of the UFH circulating pumps pending swapping it for a better pump) The house is so well insulated that the overnight temperature does not drop much, certainly not enough for it to feel cold in the morning but most mornings the heating will come on to top up each room back to it's target.

The ones I have bought are Landys & Gyr E110. I set out to buy 2 generation meters and found this guy on ebay selling 4 of these at hardly any more than it would have cost me to buy 2 from anywhere else. All I want is something I can just take a weekly reading from to log my generation and usage. I might look at the irda readers later as a curiosity project though.

Reading this thread is only serving to show that a gas boiler is not the best mate for under floor heating. I know conventional wisdom says if you have mains gas, use it as it is the cheapest form of heat. For low temperature under floor heating, an ASHP makes a much better companion. My own system is about as keep it simple as you can get. the ASHP drives the UFH directly, no buffer, and a small 5KW ASHP will happily supply water at 37 degrees and modulate down to very low levels to maintain that, and running at low temperatures like that gives good efficiency from a heat pump. I still think there is merit in individual room thermostats. We only have 3 heating zones, the big kitchen / diner space, the living room and (not yet fitted) the utility room. All loops are fed from the same temperature water from the same manifold and pretty much the same flow rates to each loop, but the kitchen / diner is the last room to reach temperature and shut off. That is simply because so much of that room does not have UFH e.g not under kitchen units or the island, not under the stove, and not under the corner of the room that will eventually be the pantry. So probably 1/4 of that room does not have heating pipes under it, so it is now wonder it takes a little longer than the other room to heat up. I have used the dry biscuit mix screed as the heat spreader medium under our wooden floors downstairs and am very happy with it. Upstairs, just in the bathrooms I have UFH with spreader plates and this does not seem as effective to me, but then again the heat has to get through the wooden floor, the wet room tanking membrane then the tiles so it is probably no wonder we get less effective heating there. Lastly with the level of insulation you will have, you WILL need separate control for the bedrooms, much of the time they won't need any heat at all, we don't have bedroom heating, but you can achieve that by just valving off the upstairs manifold as a single zone if you don't want individual room control.

I will be fitting my own export meter. More for curiosity to see how much "escapes" back to the grid. That will just be an ordinary generation meter wired backwards so it only counts up when exporting. Of course no supplier would use or trust what it says, it is purely for my own interest to see how well I am doing at self using.

I recall using Cad plated steel screws for aluminium. I used to have a table that showed what materials react with others and what doesn't. I wonder where galvanised steel comes in that table compared to cad plated?

Irelevant. Look at the video a few posts up that shows the arrangement. It does not need to be accurate.

That's exactly it. See how plain bolts and washers work fine for clamping between panels, but trying to do that for the end ones and the bolt wants to jump off sideways so needs a proper z clamp instead. He seemed just to use a rubber washer to allow for expansion.

Good point. Will look again at the "proper" clamps

picture borrowed at random to illustrate the principle The rail (in this case unistrut) will run perpendicular to the long axis of the panels, 2 rails per panel. "between" panels will be clamped to the unistrut with M6 bolts and penny washers bolting into unistrut channel nuts. So there will be a gap of 6mm between panels that I will seal by covering probably with aluminium tape. The end panels will need a Z clamp to fix them to the unistrut. Form my panel arangement I will need 8 lengths of unistrut each a little over 4 metres long. I will have 2 rows of panels and there need not be any gap at all between them and they will get the same aluminum tape to seal the joint.

The forum that keeps on giving.

For "between panels" just s simple unistrut channel nut, bolt, and washer, square washer if I can find one. It will need some form of L or Z clamp to clamp the outer edges of the end panels.

I will probably choose the 41 by 41 section pre soltted for £202, should be stronger and easier, for not much more.

Okay, am I reading this correct, ten 6 metre lengths of unistrut for £161? That sounds a bit more like it https://www.ebay.co.uk/itm/10-X-6M-UNISTRUT-LENGTHS-41MM-X-41MM-OR-41MM-X-21MM-PRE-GALV-GALV-CHANNEL/172216988267?hash=item2818eeb26b:m:mG19p5Oj7xPYbVQK22gXREw Fix the panels with M6 channel nuts, bolts and penny washers, why make it complicated?

So back to the mounting frame. My initial thought was some fence posts to make the raised / sloping structure and standard aluminium mounting rails for the panels. For my 16 panels, I will need 8, 4 metre long mounting rails and clamps. Best I have found so far is in the region of £400. That's too much. Unless someone can point me at some significantly cheaper mounting rails, then timber decking joists are looking more attractive.

Well the 14KW one will be a bit less heat output. What is your actual heating requirement? It could also be an older model, is it still showing as a current model?

The 6KVA thing, I would keep quiet. You have the same 100A connection to the local transformer so you are not personally limited to 6KVA at any one time, but if you all try and draw too much at the same time there may be issues. My guess is if you ask for more you will be hit with a hefty bill to upgrade to a bigger transformer.

Have you seen my thread about window boards? I used spare leftover oak floor boards with a bit of trim over the edges. The cill is flush, just the thickness of the trim overhangs. The small overlap of the trim covers the inevetable crack between the cill and the plaster.

So I went and pegged it all out on the ground and found it was a bit tight for space, one end of the array would have been under overhanging tree branches. So a bit of re modeling with the "cad system" By putting the panels landscape, and stepping the rows gets the width down. Not the prettiest arrangement but practicalities dictate. It increases the depth but I have plenty of that. Other news, I have been busy on ebay. I wanted 2 generation meters, but found someone selling 4 of them for less than the cost of buying 2, so I will have a spare or 2 to put on the market place. And I have been looking at inverters, and just ordered one of these https://www.ebay.co.uk/itm/Trannergy-SGN4000TL-Solar-PV-Inverter/182792629582?hash=item2a8f4a2d4e:g:fX8AAOSwJixZy6Os With todays ebay sale code, I got it for £255

15% off everything on ebay today use the code POWPOW15 Only 8 hour, be quick. I have just saved £45 off my solar PV inverter.

I have had the opposite experience. I bought my butumen roof sheets from B&Q. They have been on my wood shed roof for 10 years now with no sag and no leaks. They do need supporting every 2 feet / 60cm in both directions. Give them that support and they are fine, so your roof structure will need a lot of additions.

Search out the heat loss spreadsheet that @JSHarris has produced, download it and enter all your dimensions, U values etc and you will get a proper idea of heat loss. And the ventilation loss is a red herring, that would be the heat loss if you just ventilated with simple extract fans, but you are using mvhr so probably 90% of that "heat loss" will be recovered.

Who produced your heat loss figures? What temperature is the total heal loss figure at? and where does 2KW heat loss via the mvhr come from? I would expect that to be a lot lower. You need accurate dependable figures to start with. The 140L thermal store is WAY too small. Don't forget that with a thermal store the water in it starts to cool down as soon as you start drawing water, so typically you need a larger thermal store than you would if using an UVC instead. Another argument for a larger cylinder is the small one would not have much capacity for storing excess solar PV, and to be viable you need to be aiming for near 100% self usage.

It does. A mechanical thermostat has an "accelerator" heater wired between the Sw L out and N. It's purpose is to slightly warm the local environment to overcome the hysteresis of the mechanical thermostat. A lot of people just connect the L in and Sw L out and ignore the neutral = no accelerator heater and huge hysteresis. Mine are working just fine.

cr@p wiring usually. Even the humble mechanical thermostat has a very low hysteresis if wired properly. But forget the neutral (nah don't need that) and it's a different story.