@MK4, @papahuhu 

All heat pumps can cool (they have to be able to cool to do defrost) but some are disabled in firmware from doing so.  However as @MK4 observes the issue is not with the heat pump, its with the heating system.  Even if you operate above dew point to avoid condensation (which some heat pumps expressly do) then there are still challenges.  To cut to the chase ordinary radiators wont work, radiators with fans or UFH will.  Results reported are generally positive but you have to bear in mind that its light cooling not an American style freezer and does not dehumidify.  However maybe enough at least for our current climate and what we can reasonably expect for the next few years.

@jamespa Have you ever tried yours in cooling? I’d imagine that to get any significant cooling output the rads would be dripping condensation all over the floor. But changing the 2 way diverter to a 3 way diverter and feeding a heat exchanger in a forced air handling unit should work, in theory.

Posted by: @papahuhu

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@jamespa Have you ever tried yours in cooling? I’d imagine that to get any significant cooling output the rads would be dripping condensation all over the floor.

Quite right, which is why the only rads that will make any appreciable difference without condensation are ones with fans on (so the cooler air is actually moved into the room). It's also been mentioned plenty of times before here that rads dripping condensation over the floor (where you can see it and either catch it or clear it up) is far less of an issue than condensation on the pipes going to the rads, particularly where they are running through voids you can't see and where pooling condensate can promote rotting of woodwork and untold other horrors.

Even then, a radiator and fan at a temperature of let's say 15degC to keep it above dew point is not going to move a lot of thermal energy out of the room compared with, for instance, the thermal gain of a sun-facing window. My purely personal opinion is that it's far less hassle to let my body acclimatise; obviously, if I had a medical condition that required me to be kept cooler, that'd be a different matter.

Posted by: @majordennisbloodnok

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ven then, a radiator and fan at a temperature of let's say 15degC to keep it above dew point is not going to move a lot of thermal energy out of the room compared with, for instance, the thermal gain of a sun-facing window. 

Thats true but the solution is to shut the curtains just like they do in Southern Europe.

I tried mine (a single fan radiator in a South facing room) briefly last season and I reckon it was going to make a worthwhile difference, taking the edge off of an unpleasant environment.  Other factors meant that I didn't continue the experiment.  This year I havent tried because I was away during the heatwave but if we get another will be conducting a proper experiment.  

@majordennisbloodnok Yes, it sounds a recipe for Aspergillus Niger, didn’t think about the underfloor copper. The Swiss in their usual wisdom banned AC a long time ago, even in office blocks. Instead of coffee machines we used to have free Hagen Das machines, that added a few inches to my waistline!

A lot of the office blocks had their roofs covered with vegetation, it helped keep the buildings cooler in summer and warmer in winter. 

Posted by: @papahuhu

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Instead of coffee machines we used to have free Hagen Das machines, that added a few inches to my waistline!

That's exactly what you want; extra insulation....

🤔

@majordennisbloodnok 

evapoative cooling in the summer, it works very well. The plants transpire and whatever the substrate is dries off in the sun. I guess they must have a watering system, but don’t know for sure. Insulation works in the summer too, where I’ve added internal PIR the rooms are much cooler than where I haven’t.

Posted by: @papahuhu

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@jamespa Have you ever tried yours in cooling? I’d imagine that to get any significant cooling output the rads would be dripping condensation all over the floor. But changing the 2 way diverter to a 3 way diverter and feeding a heat exchanger in a forced air handling unit should work, in theory.

Radiator is not the biggest problem. You can deal with that bit - all the pipes in your floor and walls are also doing the same thing if you have it trying to cool. You end up needing all the pipework insulated and any condensation ending up in correct drainage spots etc.

Posted by: @jamespa

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Thats true but the solution is to shut the curtains just like they do in Southern Europe.

I tried mine (a single fan radiator in a South facing room) briefly last season and I reckon it was going to make a worthwhile difference, taking the edge off of an unpleasant environment.  Other factors meant that I didn't continue the experiment.  This year I havent tried because I was away during the heatwave but if we get another will be conducting a proper experiment.  

You'll still get to medically dangerous temperatures in many houses with the curtains closed. Even on many older buildings with the latest version of UK weather. Curtains help a tiny amount, external shutters help far more (but are not generally permitted development because UK planning is as ever far behind reality), designing houses properly with things like shading of windows from high sun would help even more - but designing things properly would be a fairly radical change in UK housing.

Our air/air was working pretty hard over the really hot days but did keep the house to a sane temperature and the solar more than covered the usage.

I can attest to the fact that insulation is the first and foremost step in shielding against heatwaves.

When we added our (mediocre I understand now compared to Northern Europe) 10cm external insulation and also painted the exterior a very light color (it was antique pink) it made a big difference in summer (in winter also of course, but our winters are getting milder and milder, we mostly felt the difference in the summer).

Window shutters help, night breeze helps, fans help, ceiling mounted fans help, portable fans with water mist help even more (in a dry climate that is). And who knows, you might come to appreciate the benefits of a noon siesta 🤣…. As I am getting older and my stamina diminishes, I have come to a better understanding of the subdued activity during summer noon/early afternoon and the excess activity late in the night…

The case of using traditional radiators or underfloor pipes for cooling has been exhausted in greek forums and the verdict is that the yield is small whereas the potential damage is massive. Anyone wanting to exploit their ASHP for central cooling has to use fancoils instead of traditional radiators.

Basically they are units with a heat exchange plate and a fan (need power to operate), are used for both heating and cooling and utilize relatively small water volume (volumizers are almost always needed). Any office building in the UK that has cooling/heating units in individual rooms is probably using them.

The quality of heating, poetically speaking, is not the same as with traditional radiators. The air heats up faster, IAT control kicks in and the building’s thermal mass is not given a proper chance to exercise its muscle. Plus you need to compensate for the created dry atmosphere (which however in country with a lot of humidity might not be a problem).

As @jamespa mentioned, all ASHPs are technically able to provide cooling and alledged restrictions are a matter of market positioning. In Greece as you can easily imagine, all units nowadays are advertised with both heating and cooling capabilities. Oh, and cooling at 35 degrees is power consuming.  

@etchedpixels 

A few warmish days or a bit of snow and the country falls apart. We’d be so screwed if there ever was a war, the Russkies are out in the freezing mud in the trenches with no rations and our lot would be worried about moisturiser supplies or painting their nails!