Thermostat settings with Immersun

PSAS786

I have an immersun (an automatic power controller that diverts surplus power to my water heater via the immersion. I am just thinking about the thermostat settings on the hot water cylinder. The cylinder stat is set to 65 degree and the immersion stat to 70 degrees - are these settings sensible and does it make sense to set the immersion to a higher temp than the cylinder to take advantage of the immersun supplying excess energy (the immersion switch is only on when the Immersun supplies 'excess' energy- i.e. when the solar panels are producing more energy than household using). I think I can see the logic in having the Immersion stat setting higher in that this energy supply is 'free' but equally I do not want to scald anyone either!
Is there an advantage in setting the immersion temp higher than the cylinder stat?
And are the current settings sensible/safe?

Cardew

Welcome to the forum.

I suggest you cut and paste the above and post it in the 'Green and Ethical' section of this MSE forum. That is where all the solar PV owners hang out and many have an Immersun or similar device; and your question has been raised before.

There is obviously a saving to be made by having the Stat higher but as you say, there is a real danger of scalding - especially if young children are likely to use hot water unsupervised.

PSAS786

Thanks I searched on this and found no results. Have not had response on different forum so happy to delete rather than move if I can do so. If not happy for mod to remove.

Cardew

You haven't posted on the 'Green and Ethical' MSE forum

http://forums.moneysavingexpert.com/forumdisplay.php?f=100

I will bring this thread to their notice.

EricMears

PSAS786 wrote: »

Is there an advantage in setting the immersion temp higher than the cylinder stat?
And are the current settings sensible/safe?

There is a considerable advantage in asking the Immersun to try for a much higher temperature than your other heat source (gas boiler ?) is asking for. But a DHW tank at 70 deg C is a bit high for safety - why not drop the 'normal setpoint lower instead ?

But to make the system safer and allow you to run the cylinder at an even higher temperature, you should consider fitting a blending valve to the tank outlet. With such a setup, I have my Immersun trying to get to 95 deg C (it doesn't very often achieve that of course) but hot water taps have a blended supply at nearer 50 deg C

pinnks

I would agree with Eric. I don't have my immersion thermostat set as high as him but have turned it up from its historic setting. We have no children in the house and most taps are thermostatically controlled mixers. Downstairs, it takes ages to feed hot water through the pipes, so it is unlikely that anyone would receive an unwelcome shock. But 65 degrees is chosen for safety reasons so a blended supply would be a good precaution.

Emmajanelouise

Hi guys.

I've recently moved in to a 1 bedroom apartment, with the immersion heater.

Just wondering how you've found yours? What's the best setting (temp) to have it on and how much is it costing you monthly if you have it on every day? I love a daily bath/shower but I'm worried that's it's going to cost too much.

Any tips or advice? (New to this as our old house had a gas boiler)

Any comments are much appreciated!!

Swipe

Emmajanelouise wrote: »

Hi guys.

I've recently moved in to a 1 bedroom apartment, with the immersion heater.

Just wondering how you've found yours? What's the best setting (temp) to have it on and how much is it costing you monthly if you have it on every day? I love a daily bath/shower but I'm worried that's it's going to cost too much.

Any tips or advice? (New to this as our old house had a gas boiler)

Any comments are much appreciated!!

I set mine for 55C but 60C would probably be better for you if you like it hot and like to add cold water. If you have economy 7 you could set it to come on for 2 hours towards the end of the E7 period.

matelodave

Our water comes on for 1.5 hours every morning before we get up and the temperature is set to 45 degrees. We've got plenty of water for a shower each as well as washing up and other sundry jobs. We've got an extremely well insulated tank so it stays hot enough for a second shower in the evening or even next morning if we get up before the heating comes on.

Cardew

Emmajanelouise wrote: »

Hi guys.

I've recently moved in to a 1 bedroom apartment, with the immersion heater.

Just wondering how you've found yours? What's the best setting (temp) to have it on and how much is it costing you monthly if you have it on every day? I love a daily bath/shower but I'm worried that's it's going to cost too much.

Any tips or advice? (New to this as our old house had a gas boiler)

Any comments are much appreciated!!

Provided your Hot water tank is modern and well insulated - usually with a dense foam cover - the loss of heat from the tank is surprisingly low. Every tank has it's heat loss tested to a British Standard with the water temperature at 65C(higher than most people will require). This heat loss is normally stamped on the tank.

For instance I have a very large HW tank and the loss is 1.3kWh(units) in 24 hours. So if I was very careful in heating just enough water at a lower temperature by using a timer, I could perhaps halve that daily loss.

A smaller tank for a 1 bed flat would have a lower loss each day.

So the cost of leaving the tank on 24/7(using electricity) should be less than 10p a day in heat loss - obviously you will pay more to heat the water you use.

I am not advocating you leave your tank on 24/7, but pointing out the penalties for doing so are not dramatic. You will have to experiment to get the water at the temperature, and quantity you require.

It is also pertinent to point out that the heat loss from the tank isn't really 'lost' as it warms the fabric of the house - which is why many tanks are in an airing cupboard.