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Originally Posted by AC_Hacker
However, you do have a very large project ahead of you, and in my opinion, you will want to choose your battles wisely.
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Ok, thanks, agreed. My direction of thought wasn't to use the existing controls and try to communicate with them. I'd leave the system to actually be quite simple, only differing parts from fixed speed would be the inverter to drive the compressor and the electronic expansion valve. The latter could be omitted at first and just using a thermal one would be the alternative. The positive thing on sourcing a inverter unit would be that it'll have a load of parts which can be used directly for monitoring and later on for control if needed, wanted etc.
For parts and tools I'm following two online auction sites (mostly liquidation sales). Currently there are a bunch of Danfoss GSHPs for sale, ending June 9th. This is very rare and I hope the interest is low (there are 3 5.7kW units available which would only be suitable for passive houses and the like). So if I come across a good deal on something like this, I will take it. Very much in line with the 'choose your battles wisely' philosophy ;-). There are many battles in the overall project.
Quote:
Originally Posted by randen
1/ building a passive house using a minimum of heat energy to remain comfortable HUGE!. Building materials of high quality are available and at a reasonable cost.
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Yes, passive house standard is the way forward. Energy not being needed keeps cost down regardless of what the government or energy companies do. However, passive house building is still an oddity here. We have a very traditional build industry and the only changes it seems to make are for satisfying the regulations, not the customers. This makes such an endeavour difficult.
Quote:
Originally Posted by randen
2/ DIY a heat pump. Yes it is very do-able. But a huge amount of work. Ask me how I know. That's why the costs to purchase one may seem a little much. As for building a electronic control for your DIY machine. I think I my humble opinion is entirely Un-warranted. They are so efficient anyway. (there's such a thing as over controlling and or over-complicating). Even the Variable frequency Drive maybe a little over-kill for a smaller unit.
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Thanks. I've been reading your thread on the 5 ton VFD unit, great work there! I agree on this comment as well as the one made by AC_Hacker. Just a variable speed on the compressor (and later on the pumps as well) could be the right direction, first starting with fixed speed. As to the amount of work, please note that I have my eyes open for good deals on commercial units, however, they are rare.
Quote:
Originally Posted by randen
3/ Combination of heated floors and Heat-Pump STELLAR!! I would suggest to install in the floor dedicated loops (plastic tubing in-expensive--Heat exchangers not so) A loop for your heat pump and one for your solar hot water.
Controlling different zones in the floor Not Required again over-controlled and added costs for valving etc.
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I'll have to continue the PHVP work but I think solar heating of the floor is of limited use, the power entering through the glazing could well be close to what would be needed during most of the year. For hot water the situation is different ofcourse. Indeed we won't control different zones, the house will naturally reach a near constant temperature. The situation of the rooms is such that the warmer ones (kitchen / living) are located south to benefit from solar heat. The cooler ones are up north. Also those thermal wax valves do consume considerable power.
We don't see off-grid as realistic yet. The grid is actually a cheaper battery than one we could buy. It could change over the years however. PV will surely by part of the house as well, trying to reduce nett electricity use to zero.
I still have some work ahead on the heat recovery ventilation as well. The idea is to run brine through a water to air heat exchanger for air entering the house. This should prevent the heat recovery system from freezing during the cold winter days. For extra (quick) heating to take care of sudden thermal changes it would be good to have such a heat exchanger after the heat recovery unit and power it with the output of the GSHP. In summer this one could aid in passive cooling.
Here again the trick would be not to make things overly complicated. Also extra heat exchangers give extra resistance and thus need more power from the fans. I'll have to find the right compromise.
As you guys know an eco friendly house is a system, it'll work as well at the weakest part.
Zwolle is close enough to be relevant. It seems to correspond quite well with Portland. London is a bit chillier for sure. However, we have had two very warm / mild winters.
Cheers,