UKC

If you have wet underfloor heating, and switch it off for the whole summer (probably around April to Sept), does it do any damage to the system?

I hope not, because that's what we do!  

Well, in fact, I don't turn it off as such, but the thermostat is set so low that it cannot possibly engage.  

Yes, I guess that's what I mean by turn off! 

Since we have moved into this house, the battle has been trying to cool it down. We have every window open all the time! Nights are still down to single figures here, and it is just about getting down to a comfortable temperature overnight! The insulation is very very effective, so definitely need a heating system which we don't need to leave on. 

I'm sure it'll be fine.  I deliberately chose very simple controls for mine - the rest of the system is so damn complex that I wanted the heat output to the UFH to be really easy to understand. So my entire heating system triggers from a timer and a single thermostat.  If the timer says that now is a time to deliver heat and the thermostat says it's cold enough, it switches on.  So, in fact, another way to completely prevent it from firing would be to remove all of the time slots that switch on, and (as you have cold nights) that might be more reliable for you.

We have similar problems with cooling; a pretty well insulated house, with two large south facing glass patio doors.  The solar gain is welcome in the winter but a pain in the summer.  I'm learning that the thing to do is seal everything up as long as indoors is cooler than outdoors, and throw everything open as soon as outdoors is cooler than indoors.  

I would assume not at would be a major design oversight, we're in the process of installing it now. Large south facing windows should help in winter, the sun should often be too high for direct sun in summer. We'll have four different zones and I'm installing Google Nest thermostats for each one. Will see how good the AI learning helps, in theory it should know the weather ahead of time and adjust since there's obviously a big lag between heating up and cooling down. 

Since we're in the mountains we tend to get hot days and cool nights and it's often hard to get the Spring/Autumn settings right but our plumber is local and seems to know what he's doing. 

A bit like with air con, or any heat system, always a good idea to just power them up and run for an hour once a month, just to cycle fluid around and keep mechanical parts moving a bit without a prolonged period of stagnation. 

Can't think why you would need to turn it off.  If the thermostat is set correctly, the system won't be providing any heat anyway.

I guess my question is more than does it do it any harm to sit idle for many months, whether that is due to thermostat not kicking in or not. It was a question about what does lack of activity do to the system, although maybe I didn't express that well. 

Sounds like we might need to run it occasionally to keep it functioning. 

OK, got it now. 

Gas boilers run the pumps and fan periodically to stop them from seizing up, even when no heat is required. It's clearly a known engineering issue, so I wouldn't worry about it. No problems with mine after 4 summers.

Cheers

Al

Worth considering things like louvred shutters if you're suffering from too much solar gain. Basically anything that blocks the sun coming directly into the windows. 

Depending on your thermostats, they may have a 'valve protection' or similar setting which cycles the system every week or two automatically if the system hasn't otherwise run.