Greetings my fellow heatwave sufferers! Over here, we navigated May unscathed and we are bracing for June.

I wonder if I will live to see window shutters becoming the norm in the UK as they are in South Europe. Sooner than that I expect Mars and the users of the forum to open topics on using the cooling capabilities of the ASHPs. Till then and speaking from first hand experience, plain fans can be real relief. 

Below is our May output. You can see that this year we had more overcast days in May. 1st of May in particular was like November…

@mk4 

I was thinking about that too. From what I understand, all ASHPs can cool, it’s just that if they cool the rads they will drip condensation and rust. I was wondering if you could add a diverter valve that fed the cool supply to an air handling unit in the loft that fed cool air through vents in the bedroom ceilings. In theory, that cooled air should sink downstairs to knock the edge off the heat there too. I guess there would need to be a condensate line on the air handling unit to minimise any mould growth and maybe some sort of bag or panel filtration too. Doesn’t seem massively complex.

@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

↑

@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

↑

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

↑

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....

🤔