Post and beam Posted June 18 Share Posted June 18 I have been advised to steet clear of using the ASHP in cooling mode due to a very fine line between useful cooling and hitting the dew point with resultant condensation. Anyone got real world experiences good or bad to share please? Link to comment Share on other sites More sharing options...
JohnMo Posted June 18 Share Posted June 18 All depends on how you cool. Due point is really only an issue when cold hits the atmosphere. I use it in UFH, I flow down to 12 degs, which is at or just below dew point. But I don't run all the time. I will do about 3 hours in the morning and then about 4 hrs in the afternoon. Floor surface gets to about 19ish, so well above dew point. It doesn't make the house cold, it tempers the temperature, but more importantly feels cooler than it really is. UFH radiates heat at you, in cooling mode it suck heat from you, so you feel cooler. If you have radiators don't bother it doesn't work. If you have fan coils you can have a nice cool house. Ignore the nay sayers, they probably have never tried. If you want cooling on all the time you need to be careful with flow temp and about 1 Deg above dew point should be fine. 2 Link to comment Share on other sites More sharing options...
JohnMo Posted June 18 Share Posted June 18 Forgot to add, I work on the principle that I try to keep the house cooler than outside as long as I can. Once it cooler outside than inside, cooling is switched off and doors, windows opened. Link to comment Share on other sites More sharing options...
MikeSharp01 Posted June 18 Share Posted June 18 3 minutes ago, JohnMo said: flow temp and about 1 Deg above dew point should be fine @Post and beam don't forget that dew point moves about with relative humidity (RH) so any control system will need RH and temperature inputs to calculate the dew point. A simple equation can be found here although , as the author points out, it gets wobbly below 50% RH. 1 Link to comment Share on other sites More sharing options...
ragg987 Posted June 18 Share Posted June 18 I've used mine in cooling mode for the 7 summers that we've been here. Works well for us, I added solar shading to the large south and east facing windows and this helps a lot. As above we have flow set around 12C and run it for a few hours consuming excess solar power. It makes a big difference, though not the same as Aircon. Our MVHR will switch to heat exchange mode when it is too warm outside, that helps. And on a cool night we open windows to help. I added an Aircon kit, essentially some insulation and a drip tray. There is usually condensation in this area, and downtimes also on the copper pipes leading to the UFH manifold. Nothing excessive and seen no issues so far. Link to comment Share on other sites More sharing options...
Dan F Posted June 18 Share Posted June 18 25 minutes ago, Post and beam said: I have been advised to steet clear of using the ASHP in cooling mode due to a very fine line between useful cooling and hitting the dew point with resultant condensation. Anyone got real world experiences good or bad to share please? Also depends what ASHP you have. Some have dew point monitoring which will ensure you can avoid condensation. Link to comment Share on other sites More sharing options...
Post and beam Posted June 18 Author Share Posted June 18 My potential ASHP and UFH installation company are very wary of cooling. I had settled on a Vaillant 7kw unit. Installer agrees but has an additional suggestion of a veissman vitocal. When i asked about cooling he was very, well , cool about the idea. In that he thought it was a bad idea. UFH and a large 75mm slab would provide a nice mitigation of summer temperatures i thought. Link to comment Share on other sites More sharing options...
nod Posted June 18 Share Posted June 18 13 minutes ago, Post and beam said: My potential ASHP and UFH installation company are very wary of cooling. I had settled on a Vaillant 7kw unit. Installer agrees but has an additional suggestion of a veissman vitocal. When i asked about cooling he was very, well , cool about the idea. In that he thought it was a bad idea. UFH and a large 75mm slab would provide a nice mitigation of summer temperatures i thought. I had three quotes ALL dismissed it as a bad idea Though I have read somewhere that it would effect the BUS grant Which may explain why they are not keen Link to comment Share on other sites More sharing options...
JohnMo Posted June 18 Share Posted June 18 14 minutes ago, Post and beam said: Vaillant 7kw Needs additional kit to make it cool. Vaillant will want a few hundred, others a couple of pounds I have the same as a Vitocal 100, but badged by the original manufacturer. Easy to set cooling. Link to comment Share on other sites More sharing options...
JohnMo Posted June 18 Share Posted June 18 2 minutes ago, nod said: would effect the BUS grant In the old days yes, now makes no difference. Link to comment Share on other sites More sharing options...
Post and beam Posted June 18 Author Share Posted June 18 16 minutes ago, JohnMo said: Needs additional kit to make it cool Do you know what that is? Link to comment Share on other sites More sharing options...
Nick Laslett Posted June 18 Share Posted June 18 (edited) 2 hours ago, Post and beam said: I have been advised to steet clear of using the ASHP in cooling mode due to a very fine line between useful cooling and hitting the dew point with resultant condensation. Anyone got real world experiences good or bad to share please? ASHP cooling is one of the cornerstones of my design. I didn’t want to install AC. You may only need active cooling on average 3-4 weeks* a year in my part of England, but it sure would be nice to make things a little cooler during those times. There are a number of different strategies you can deploy for cooling. I chose to have UFH both downstairs and upstairs in insulated concrete slabs. These slabs will create a cold heatsink to cool the whole house. I only put in the UFH upstairs for the cooling. You can set the ASHP weather compensation curve to be 2°c above the dew point. You would also insulate the pipe work. Is there a risk the UFH pipes in the slabs will cause a problem, to be honest I don’t really know. All the other associated pipework is visible to inspection in my build. The weather has been so poor this year, that I’ve only had the cooling mode active on 2 occasions just for fun. My system was only commissioned in April. *this is a made up figure. I have no idea how many evenings a year have temperatures above 27°c. Although the Met Office told me this May was the hottest on recorded, so forgive me for being very sceptical about any official data. Edited June 18 by Nick Laslett Link to comment Share on other sites More sharing options...
JohnMo Posted June 18 Share Posted June 18 1 hour ago, Post and beam said: Do you know what that is? Some sort of plug, it been discussed on here before, think they use the same plug on boilers and heat pump, heat pump it's for cooling (£x00) and on boiler for some other function (£x0). Link to comment Share on other sites More sharing options...
JoeBano Posted June 18 Share Posted June 18 I’ve just upgraded all my bedroom rads to myson Ivectors fan coil units about a month ago (absolute bargin new old stock) They cool my bedrooms far quicker than I expected, cooling 23c to 19c around 1-2 hours. Been looking for condensation, running flow temperature around 11-12c, Not noticed any yet after 1-2 hours but I will be fitting a dew point sensor for my heat pump which probably need when we hit the 30c days. Link to comment Share on other sites More sharing options...
sharpener Posted June 18 Share Posted June 18 4 hours ago, JohnMo said: Needs additional kit to make it cool. Vaillant will want a few hundred, others a couple of pounds Here you go, link was posted recently on Arotherm plus FB page https://www.theheatxchange.co.uk/vaillant-plug-coding-vai0020266328. Link to comment Share on other sites More sharing options...
Post and beam Posted June 19 Author Share Posted June 19 10 hours ago, JohnMo said: Some sort of plug, it been discussed on here before I had a feeling thats what you would say. In which case, its a resistor across two of the pins on the plug. If its only two pins it will be across both of those. 20p to make your own, Max. Link to comment Share on other sites More sharing options...
Post and beam Posted June 19 Author Share Posted June 19 7 hours ago, sharpener said: Here you go, link was posted recently on Arotherm plus FB page https://www.theheatxchange.co.uk/vaillant-plug-coding-vai0020266328. There you go then, i replied to the earlier post before seeing this. At £6 delivered i would not even bother to make one. In fact i might buy one just to measure what the resistor value is. My curiousity is getting the better of me. Link to comment Share on other sites More sharing options...
Blooda Posted June 19 Share Posted June 19 Discussed here as well. 4.02kΩ ±1%. 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted June 19 Share Posted June 19 really need a setup that constantly monitors the changing dewpoint and adjusts flow temp accordingly. I use Home assistant as it talks to the Panasonic aquera directly so makes the whole thing seamless. Link to comment Share on other sites More sharing options...
JohnMo Posted June 19 Share Posted June 19 47 minutes ago, Dave Jones said: really need a setup that constantly monitors the changing dewpoint and adjusts Or a thermostat like a Computherm Q20RF will do heating and cooling and adjust room temp target based on humidity when in cooling mode. Link to comment Share on other sites More sharing options...
Conor Posted June 19 Share Posted June 19 (edited) Is intermittent condensation really an issue in the summer? A few hours / days a handful of times during warm weather, with low absolute humidity, isn't going to cause any problems? Totally different for chronic, cold weather condensation. As long as it's not forming on your lovely wooden floors, of course. Edited June 19 by Conor Link to comment Share on other sites More sharing options...
Dave Jones Posted June 20 Share Posted June 20 8 hours ago, JohnMo said: Or a thermostat like a Computherm Q20RF will do heating and cooling and adjust room temp target based on humidity when in cooling mode. don’t use thermostats . Full weather comp is way to go . Flow temp set and forget 1 Link to comment Share on other sites More sharing options...
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