Gone West

I removed both copies of the blog when I sold the house. The 13kWh/m2a was for space heating only but I can't remember for sure whether the energy for running the Genvex was included in that. I would have thought the PHPP would have included the Genvex energy used and the heat recovery though because I bought a version upgrade for PHPP from 2007 to 2010 that included built in compact unit data which included the Genvex Combi.

I've always read that COP was P out/P in which is why SCoP is supposedly more accurate. Is that wrong?

I would prefer a stainless steel or copper tank and not have an anode. I had a Genvex Combi 185L unit which had a 585W EASHP which heated the tank. The tank was enamelled steel and had an anode. The warranty for the unit was only two years. COP is P out/P in, so I don't know how Dimplex have done their calculations.

One of the mistakes I made fitting the ducting on my system was to fit an attenuator on the supply circuit and not on the extract circuit. I didn't think it would matter as the extract vents were only in the bathrooms, kitchen and utility. The rooms with supply vents were silent but the bathrooms etc had a slight background hum only audible in the room itself. If I ever design another system for myself I would use two attenuators. https://www.ductstore.co.uk/acatalog/Attenuators.html

Yup, well in a PH. If you're not pumping loads of heat in low down, how is it getting to the ceiling. The heat has to be coming from somewhere. If the UFH is only a degree above room temperature the gradient is shallow. If you have hot radiators there is a steep temperature gradient and the hot air travels upwards quickly, cooling as it goes, until it drops down for the cycle to be repeated continuously.

Well you beat us by a year, well done.

We had a tiled ground floor in our PH without UFH. We heated the house with three towel rails in the bathrooms, supplemented with warm air from an EASHP, and kept the air temperature at 23C. The floor never felt cold and I measured the floor temperature and it was always between 22C and 23C. Warm air only rises to the ceiling because of the temperature gradient. If the house is well insulated and the ducted warm air came in at floor level at a low enough temperature it wouldn't rise straight to the ceiling.

There are small A2W heat pumps that heat just a water tank. There might be more than these. https://www.ariston.com/en-uk/products/air-source-heat-pump-water-heater/air-source-heat-pump-water-heater/ https://www.earthsaveproducts.com/products/ecocent

You're lucky, as I was, to have a very low energy house. I found my house was very comfortable without any conventional heating. Most of the people the government are pushing to have ASHP and hence UFH don't have low energy houses. When you try to fit UFH in an unsuitable house the 8% goes up because the temperature gradient is steeper as a result of needing higher water temperature. That combined with limited under floor insulation means a significant amount of the heat is lost.

I don't understand why people go to the effort of insulating and draughtproofing their houses and then put in a heating system that directly sends a certain proportion of that heat into the ground. IIRC Jeremy calculated that he lost 8% to the ground through his 300mm EPS underfloor insulation. Using radiators is more efficient but even then, heating water to heat a concrete slab or metal radiators to then heat the air seems daft. Why not just heat the air directly, A2A. Over the years I've read on GBF about contributors who use A2A successfully. https://www.aircon247.com/p/9324538/lg-mu5r30u40-88kw-multi-split-outdoor-unit-r32---202122.html Rant over.

The ducting can be bought separately from the MVHR unit and can be metal, rigid plastic or flexible plastic. The ducting design can also be serial or manifold. I designed my own system which was a serial, rigid plastic ducting design connected to an expensive Danish compact unit. You can choose what you want.

The airtightness is only important when it's colder outside than inside. In the summer the windows can be opened any time you want.

Our stairwell came off the central hall room and the landing served three bedrooms and a bathroom. The bathroom had a roof window and in the summer, when it was hot, we opened the entrance door and the roof window, in the evening, to create a passive stack effect. It was amazing how much air movement there was and how effective it was at dumping the hot air. We tended to live with all the internal doors open all the time so air moved around the house.

No, the PH concept is that all rooms are the same temperature. In the PHPP there is one temperature input data which by default is 20C but which is a variable.

We've got views of the upper reaches of the River Tamar from our sitting room and bedroom. Simply fantastic.

I guess it's in preparation for when it's mandatory to build cars with speed sign recognition and speed limiters. Most new cars have speed sign recognition so it's only one more step.

We recently bought an AEG 600mm induction hob from Currys with one week delivery. We have ordered an AEG oven, combi oven and fridge freezer from our local Euronics store. The ovens are 3 to 4 weeks delivery and the fridge freezer 18 weeks delivery.

Was there much deflection on the original joists before sistering them?

We used an Isoquick insulated raft foundation and the insulation is called Peripor which is a type of EPS300. IIRC we were told it had been used in Canada for commercial buildings. The Structural Engineer will ensure it's suitable for your use.

Yes that was what I used on a previous house. I cut the clay pipe with a chain cutter I hired.

PHPP defaults to an internal temperature of 20C but that is an input variable so you can run it at any temperature you like.

@Smallholder I designed and built our 120m2 PH using PHPP and the calculations were done at 20C and came out at 13kWh/(m2a). We actually ran the house at 23C 24/7 and the calculations for that were 21kWh/(m2a) which turned out to be pretty accurate after living in it for three years. We heated our house with a towel rail in each of the three bathrooms and supplimented that with an EASHP providing warm air when very cold. We also had a solar gain area which helped in the spring and summer. Our U factors and air tightness were much better than the minimum PHPP requirements. We were near the coast in Kent. You have to be very careful comparing PH energy values as climate and interior/exterior temperatures make a big difference to energy requirements.

Oh to be young again .

I think we really are PH type people because we've just taken out a woodburning stove from this place and sold it to our neighbours. I remember from decades ago when I had a woodburner about the work involved in cutting and storing the logs, the dust and having a toasted face. It's the last thing I would want these days, lucky we are all different.

We used Schock composite granite sinks in our last place. They were black underhung on black granite.