IainH

Thanks for the reply. There was a serious pressure imbalance between hot & cold as we had a second (unregulated) cold water feed direct from mains at 12 bar into the original build that took some working out as to why the hot water at 3 bar (set with PRV) was not getting anywhere! That was resolved, but the running out of hot water issue still remains with the secondary circuit being the prime suspect. Still working on it.

That, I think is the problem. Will try switching the pump off / playing with different pump timings. Thanks.

It's not 9000 M2 (and sorry for any confusion). The 7700 Sq ft barn has planning (with some works commenced, so now in perpetuity) but is still undeveloped. For our build we joined two existing 2000 sq ft barns with a new 1600 sq ft link to give total 5600 sq ft so around 520 M2. Also, as we are on the DRHI scheme, we are not allowed secondary energy producing equipment. I don't like the looks of PV but would have a wind turbine when the DRHI scheme is finished.

Thanks again for replies. The house is holding it's heat fine but when there was long periods of DHW heating during the winter when the timer was wrong, it would cool down. Please see attached photo of our hot water tank. Thermostat pockets are in the middle and top of the tank - both unused. The electric immersion at the bottom of the tank was only wired very recently ("we forgot that bit"- even though it was MCS inspected) and, as far as I understand, is only an override should the boiler fail? The hot water works at the moment only on the three times a day timer (soon to be twice a day) and seems only to be on or off - or is the GSHP getting a temperature reading via the wiring for the electric immersion heater? We just has two showers and only achieved that with a DHW boost. Something ain't right so we will try with the secondary pump off & see what happens.

Thanks for both replies. My responses are below - 1. By "on demand" pump I was thinking of a pump activated by impeller movement, not just by someone entering the bathroom. Turn on the hot water, impeller moves, pump kicks in? 2. On underfloor heating and DHW I understand NIBE GSHP's can dual function? 3. I will try DHW twice a day only and 4. I have already reduced pump speed from max (3) to min (1). The problem with timing is I that am a lark and regularly up before 5am whilst my wife is an owl who rarely gets in bed before 2am to awake at the crack on noon. Children were conceived by correspondence! I will also check the cylinder thermostat - but I'm not 100% sure the tank is communicating to the Kensa.

I was just about to post about our hot water problem, but then saw this post. Brief update of where we are - In 2018 we got change of use and then full planning for three barns, started our build in March 2019 with the intention of building a 2000 sq ft barn, selling our existing house, move into small barn then build the "grand design" 7700 sq ft with glass gable ends etc etc. During the build we had further thoughts on the end product, ceased the build for nearly a year to get planning for linking two existing barns with a third new build barn - giving three sides of a rectangle layout, with courtyard in the middle. Despite being in year six of a two year plan, the end product is much better than the original and we are very happy with it ....but, we have a hot water issue. Our Kensa GSHP cannot heat the house and hot water at the same time with DHW having priority. This means that when the water is being heated, the building is not. After tweaking the room stats and the water heating times three times a day to 50c, we have a working system BUT, we cannot get two showers out of a 305L tank. The bottom of the tank seems to be constantly cold plus, due to the distance between GSHP and kitchen etc, we have a secondary hot water circuit pumping from 0600 to 0200. This was running in mode 3 (4.3M3 / hour) which we have reduced to mode 1 (no idea of water volume, but made little change). So, 4300 litres of water an hour through a 305 litre tank means that the water is being circulated 50m - 60m fourteen times an hour. The circuit is very well insulated but, if each circuit drops 1 deg c then the water is cooled well below shower temperature, and if two showers are required we have to boost the water to ensure there is enough hot water for the second shower. Is there such a thing as an on demand pump that will only pump only when water is demanded or is there any alternative solution please? Boiler installers and the plumbers are both out of ideas. Thanks in advance. PS. There are only three on and three off options on the secondary pump timer.

I know this is an old thread but some people (like me, might have the same problem ) but according to this Government documentation.. https://www.gov.uk/government/publications/how-to-switch-your-bulk-liquified-petroleum-gas-supplier/advice-on-switching-bulk-lpg-supplier see "What happens to the LPG tank when you switch?" "You should not be charged for the removal of existing tanks."

Is there a link to where I can find this in the regulations please? Thanks in advance.

Can anyone give me a price idea please for plaster boarding and plastering the four walls and ceilings of two small rooms - 2.1m x 2.4m and 2.1m x 2.15m plus the ceiling only of a third room 4m x 1.6 Thanks in advance.

Thank you. ?

Would anyone have a link to a step by step guide to the submission process please? TIA Iain

Based on our AC system in the US (where Daikin - who we'd never heard of when we renewed our whole AC system some years ago - are highly respected ) we can't recommend Daikin highly enough and will be installing a Daikin hybrid (ASHP + LPG) system in our new house in the UK. Price is one thing but cost of ownership is another?

Thanks for both replies. After on site discussions today, the consensus from two trusted installers is to use a separate lpg boiler for the smaller unit. We do have 3ph on site but that complicates things if we went for an industrial installation. As someone said "keep it simple, stupid" (me, not anyone else). Thanks again.

Advice much appreciated please. The house we are building will have hybrid ASHP/LPG powered under floor heating. Using the same equipment can I also heat a separate (180M2 with garage, workshop and 2 offices) which is 30m away from the dwelling - or will I need (or would it be best to have) a separate boiler? Thanks in advance.

..No. sorry. Working cocker.