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Jimlad

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  1. Hi all, I'd really appreciate the input of members here on the best approach to modernising the heating setup for a fairly large property which we're just about to start the refurb on. The house is approx 385m2, dating back to early 1900's and has solid 400mm thick stone walls. A room by room heat loss calulation gave a 26kw heating load at -2c design temp and that includes the feasible fabric upgrades which we have planned. We have an existing array of 8kw solar PV which in the last 12 months generated 6400kwh of leccy. We don't currently own an EV but that's definitely a possibility on the horizon. Current heating and DHW are powered by an ancient oil boiler with open-vented cylinder (albeit with a new burner fitted in the boiler in the last 3 years) and we went through 3500 litres of oil last year (gulp), and that included a period of "just put a jumper on", when prices were at the absolute peak of madness. The hosue is hugely over specced in terms of rads (e.g. living room has a heat loss of approx 2kw but has almost 5kw of rads capacity) Priority number one is to reduce our fuel bills and it seems like a no-brainer to do as much with the fabric as possible and also have an iBoost or similar installed to dump excess PV generation into DHW. Beyond that, I'm really torn as to the best approach in term of the type of system to specify for that kind of heat load. We don't have a huge budget and there's lots of other jobs that need doing so ground source is out of the question. Ideally we'd completely remove any reliance on fossil fuels but it seems that would mean cascading multiple ASHPs to get the KW rating we need, which then becomes quite expensive. I have spotted that Cool Energy do a 3 phase ASHP which goes up to 32KW but it looks to be quite noisy (70dB) and would only just cover the load required. Another option would be the Grant Hybrid, although that would obviously still tie us to oil somewhat. Thoughts and opinions about the best way to proceed very gratefully received!
  2. The heat interface unit is a heat exchanger and instantaneous heater contained in one unit. It uses the ASHP to heat the DHW via the exchanger and then the instantaneous heater kicks in when necessary. (or at least as a layperson that's how I understand it.) Info attached if you're interested. Model in question is the WSG-2-DUO. I've attached the plans so you can see the layout. It's actually 3 floors but the 1st and 2nd extend over a shop so the building is larger at those levels than the ground floor. STE_TB_Heat_Interface_Units_en_INT.pdf
  3. There will be 10 showers, no baths and running out of hot water is a definite no-no! We are restricted by the design of the roof so cannot fit any PV, so presumably solar thermal is also out of the question. Site also precludes GSHP. Thanks for the mention of CO2 heat pumps, i've not read up about those so will do some reading around that option.
  4. Hi all, I'd like some advice please - i've spoken to two installers and had two completely conflicting opinions so some impartial advice would be really helpful. The property is 309 m2 and is a large shared house with 10 ensuite bedrooms, essentially a small hotel I suppose. Building fabric will be at the following U-Values: Ground Floor slab - 0.12 - with wet underfloor heating - 50m2 approx External walls - 0.21 Roof - 0.13 So far, the two options suggested are: Option 1 Steibel Eltron WPL 25 AS ASHP 100l Buffer tank 2 x three-phase Heat Interface Units - just for DHW when demand outstrips ASHP capability As i understand it the ASHP pre heats the HIU heat exchangers which pass through DHW and only kick in when the flow rate or overall demand necessitates the extra electric power to maintain temp. This gives us a benefit in not having to store large amounts of hot water. I'm concerned that the heat pump isn't man enough to tackle the floor area in question however. No in depth heat calcs done yet but assumed at 45w/m2 = 13.9KW as a minimum. Option 2 Vaillant Hybrid system with ASHP and Gas System boiler Unvented cylinder/s - size not defined yet Explained to me as better than option 1 as the boiler will always be there to pick up any slack for either DHW or Heating. We have to use renewables as a condition of planning and an ASHP specifically. I'm keen to claim against the RHI as well. I've no experience with renewable technology on any previous projects so any nuggets of wisdom greatfully received!
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