Guest 34 Posted January 4 Share Posted January 4 This article clarifies what I'm talking about (the term has different meanings to different people). https://www.linkedin.com/pulse/is2-heat-pumps-cascade-graham-hendra/ I'm only looking for the second stage (i.e., the indoors heating pump). As in, a water-to-water monobloc heat pump that is not a GSHP system. I'm looking for something that is small and any plumber could plumb in that simply boosts the flow temperature of a hydronic heating system by lowering the temperature of the return pipe. These systems are usually quite big and expensive as they are only used in the commercial space. The closest consumer grade product I've found is the Mixergy iHP (Daikin, Vaillant, Dimplex and others have similar offerings). They are indoor heat pumps that take low entropy created by your central heating system (gas boiler, monobloc ASHP, air-to-air mini split, etc...) and concentrate it to give you hot water (higher temperature than what your heating system provides). The link between the two stages in this scenario is too weak and inflexible (CH, heats water in pipe, pipe heats emitter, emitter heats air, iHP uses air to heat up a coil..., hot water). I'm looking for something that is very small, something the size of a portable air conditioner or even a dehumidifier (200 electrical watts or thereabouts). Instead of fans and radiators, you would have braised heat exchangers (kind of like the desuperheater pool heaters you can find in the US, but again, smaller). You would connect your return flow pipe to the evaporator heat exchanger and the flow to the condenser heat exchanger. That way, you can use your central heating (whatever it is, you just need it to produce hot water that circulates) to heat your hot water tank. In the case of a gas/oil boiler, you can make it more efficient as you would be lowering the return pipe temperature (I know about gas savers, I'm looking for something different). Link to comment Share on other sites More sharing options...
SteamyTea Posted January 4 Share Posted January 4 An interesting idea. I wrote an assignment on a cascading PV/Storage system a couple of decades ago. Was totally impractical at the time because battery storage was extremely expensive (got marked down for that, even though price was not in the remit). The nearest I can think of to do this sort of thing is an ordinary HP of some sort and then an EAHP to get the higher temperature. @Gone West has one in his old house and it worked well. I think the real problem is that it is cheaper and a lot easier to just boost up stored water temperature with a £30 immersion heater in the cylinder. If a 'magic box@ was available, even at £500, that is the same as buying in 6,120,000 kJ of electricity. 85 kJ will heat 1 litre of water by 20K. So 72,000 litres of water can be heated for 500 quid. If a shower takes 25 litres of 60°C hot water, say 100 lt for a family of 4, then that is 2 years worth. Or about 16 years worth for me as I take short showers and I live alone. I like the idea, but would want a system that has it built in already i.e. 2 wet outputs, on for the CH and one for the DHW, while still delivering a SCoP of over 3.5. Link to comment Share on other sites More sharing options...
JohnMo Posted January 4 Share Posted January 4 Sorry your long post has just confused me. In short form what are you trying to do and why? Get the bit about a cascade system, adding additional heat. Are you trying to build a hybrid system or something else. Your system seems to want to rob pre heated add some more heat to use else where. Why not just heat it directly? Link to comment Share on other sites More sharing options...
Gone West Posted January 4 Share Posted January 4 2 hours ago, SteamyTea said: @Gone West has one in his old house and it worked well. The EASHP in the Genvex 185LS I had, was rated at 585W. I don't know how it worked to heat the water, as it just switched between heating the water in the tank to heating the air in the MVHR ducts. Ground Sun produced a small ASHP a while back called GS200. Link to comment Share on other sites More sharing options...
Guest 34 Posted January 4 Author Share Posted January 4 EASHP still use air as their source and usually have a DHW cylinder attached to them so not as flexible in what applications they can be used in. A 2nd stage cascade module would be a water-to-water (4 ports, all water pipes) mono bloc heat pump (or gas heat exchange ones but you need all the associated refrigeration equipment to install them). It seems they only exist in the commercial space. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 4 Share Posted January 4 3 minutes ago, Pevel said: It seems they only exist in the commercial space. Do you have a link to an example? Link to comment Share on other sites More sharing options...
JohnMo Posted January 4 Share Posted January 4 12 minutes ago, Pevel said: EASHP still use air as their source and usually have a DHW cylinder attached to them so not as flexible in what applications they can be used in. A 2nd stage cascade module would be a water-to-water (4 ports, all water pipes) mono bloc heat pump (or gas heat exchange ones but you need all the associated refrigeration equipment to install them). It seems they only exist in the commercial space. They exist in the domestic sense also. I did see a link on here for one. Took UFH return water, stripped away some heat, and added the water back into the system via close coupled tees. Think it was a french company making them. It had a CoP of around 4. But all the energy you strip from the water has to be added from elsewhere later. So didn't really see any advantage. Physics doesn't work like this, you don't get anything for nothing. What are you trying to achieve? Link to comment Share on other sites More sharing options...
SteamyTea Posted January 4 Share Posted January 4 23 minutes ago, JohnMo said: Physics doesn't work like this, you don't get anything for nothing. Too right Energy can neither be created nor destroyed, but only changed from one form to another Link to comment Share on other sites More sharing options...
Guest 34 Posted January 4 Author Share Posted January 4 1 hour ago, JohnMo said: They exist in the domestic sense also. I did see a link on here for one. Took UFH return water, stripped away some heat, and added the water back into the system via close coupled tees. Think it was a french company making them. It had a CoP of around 4. But all the energy you strip from the water has to be added from elsewhere later. So didn't really see any advantage. Physics doesn't work like this, you don't get anything for nothing. What are you trying to achieve? Yes that's what I'm looking for. The energy will be added by the boiler. Do you happen to remember any keywords (topic, company, product name, etc...?). Link to comment Share on other sites More sharing options...
JohnMo Posted January 4 Share Posted January 4 Is this what you are looking for? An expensive solution to make hot water. https://warmtepompboilershop.nl/product/auer-edel-eau-200l-warmtepompboiler-2/ Made by AUER France Link to comment Share on other sites More sharing options...
Guest 34 Posted January 4 Author Share Posted January 4 Hmm almost. It is indeed very expensive considering there won't be much in the way of support in the UK for this product. In the second page, you see two pipes nicking some heat from the return pipe which then gets stepped up and dumped in the water cylinder. This is half of what I hoped might exist. So forget about DHW for now and consider another application for a water-to-water HP. Just erase the cylinder in that picture and replace it with two more pipes. Those pipes would be hotter than the flow provided by the outside HP. In my case, I have two UFH manifolds but one needs a higher flow temperature than the other. I know I can get an electronic valve mixer for the UFH that needs a lower flow temp and set a higher heating curve on the boiler so that the other UFH zone gets hotter. No luck finding anyone that would do this in my area though which is why I'm just day-dreaming on an internet forum before bedtime 😅. If I could get a heat pump to boost the flow temperature, on just the one manifold that needs it, I could keep my boiler's heating curve low AND increase condensation efficiency (by making the return colder, without increasing the flow temp). So yes, I'd use more electricity and gas, but it still might be more efficient than just increasing the flow temp and having one zone constantly overshoot. Thanks for digging that up though. Seems like a great product, shame about the price. Link to comment Share on other sites More sharing options...
JohnMo Posted January 4 Share Posted January 4 Sorry to be blunt Your idea is strange. Can't find anyone to install an electronic mixer, but expect someone to do this odd ball idea - no chance. Practically your idea is not even worth doing. Hot manifold run direct, no mixer, other manifold Ivar mixer. Once your boiler return temp drops below about 50 you are chasing points of a percentage gain in efficiency anyway. Link to comment Share on other sites More sharing options...
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