CalvinHobbes Posted May 13 Share Posted May 13 (edited) Who could I send my plans to so we can get the plumbing done to suit the ASHP so pipe sizes and radiators, ground floor is correctly sized and we can get on with it while shopping around for the actual pump or even go 2nd hand? A lot are ripping them out I hear due to crazy electric bills. Ni hasn't got its grants in place yet, nor sufficient trained installers. The plumbers merchants told us we would need a 10kw ashp so looking on eBay just to see! Edited May 13 by CalvinHobbes Link to comment Share on other sites More sharing options...
sharpener Posted May 13 Share Posted May 13 Start with a proper heat loss calculation. Have you looked to see if there are any Heat Geeks in NI? If it is a new build does your architect or mech services designer not know someone who can do this? If you know the fabric/construction details you can download Heatpunk s/w free from Midsummer website and do it yourself. Pipe sizes should roughly be one size up on normal rad system design bc the low delta-T (typ 5 deg) means higher flow rates than in a boiler system, and certainly not microbore. I would not expect a plumbers merchant to have the faintest idea about correct HP sizing unless he happened to have a personal interest for some reason. Link to comment Share on other sites More sharing options...
CalvinHobbes Posted May 13 Author Share Posted May 13 The plumbers merchants has a special dept that sells them and specs the radiators etc. Ok thanks will try and use the midsummer option and maybe look for a mechanical services person Link to comment Share on other sites More sharing options...
nod Posted May 14 Share Posted May 14 We had three quotes ALL came back with the same calcs Like many things They seem to use the same software 1 Link to comment Share on other sites More sharing options...
CalvinHobbes Posted May 14 Author Share Posted May 14 (edited) So 2nd quote in and it gave quite a lot of info. Only thing is they missed that it's 3 phase. Is there anything you think I should ask? Also I thought we had to get aluminium rads upstairs? Edited May 14 by CalvinHobbes Link to comment Share on other sites More sharing options...
JohnMo Posted May 14 Share Posted May 14 Thought you building a passivhaus or close too. Sounds like you are being quoted for a ventilated shed. 1 Link to comment Share on other sites More sharing options...
CalvinHobbes Posted May 14 Author Share Posted May 14 I keep thinking that too. Anyone recommend a mechanical services engineer? Link to comment Share on other sites More sharing options...
sharpener Posted May 14 Share Posted May 14 (edited) 10kW is massive for a modern house, maybe up to 400 sq m. This unit will actually produce 11.6 kW at -1C OAT and 45C flow so where did they get the 10.8 from? see the chart below. The 7kW unit will produce 9.25 kW under the same conditions so is spot on for your heat loss. This will make a big difference as the 10kW is really a dumbed down 12kW and is likewise a twin-fan unit so too big (in England) for deemed planning permission and needing a planning application. Do you really want the bedrooms to be at 18C, many ppl would find that uncomfortably hot. They have shown rad flow 45C return 35C. But the Vaillant HP will always produce 5C delta T so something is wrong here too. The schematic shows a buffer (why?) but only a single, UFH, heating circuit however there is a schedule for radiators as well. The parts list does show a VR71 wiring centre which you will defo need to control rads + UFH + DHW. It should appear on the schematic as item 12e but it is not there, confirming they have proposed the wrong schematic. Edited May 15 by sharpener 1 Link to comment Share on other sites More sharing options...
CalvinHobbes Posted May 15 Author Share Posted May 15 3 hours ago, sharpener said: 10kW is massive for a modern house, maybe up to 400 sq m. This unit will actually produce 11.6 kW at -1C OAT and 45C flow so where did they get the 10.8 from? see the chart below. The 7kW unit will produce 9.25 kW under the same conditions so is spot on for your heat loss. This will make a big difference as the 10kW is really a dumbed down 12kW and is likewise a twin-fan unit so too big (in England) for deemed planning permission and needing a planning application. Do you really want the bedrooms to be at 18C, many ppl would find that uncomfortably hot. They have shown rad flow 45C return 35C. But the Vaillant HP will always produce 5C delta T so something is wrong here too. The schematic shows a buffer (why?) but only a single, UFH, heating circuit however there is a schedule for radiators as well. The parts list does show a VR71 wiring centre which you will defo need to control rads + UFH + DHW. It should appear on the schematic as item 12e but it is not there, confirming they have proposed the wrong schematic. Tremendously appreciated! I have sent him your comments and will report back. Link to comment Share on other sites More sharing options...
sharpener Posted June 26 Share Posted June 26 Was there any outcome to this @CalvinHobbes? Link to comment Share on other sites More sharing options...
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