Sun, 03 May 2026 11:31:06 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298081#Comment_298081 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298081#Comment_298081 Fri, 07 Oct 2022 10:14:34 +0100 neelpeel The room is insulated, but I still think it must waste a great deal of heat, especially in the summer when the heating is switched off and only the hot water is left running.

The wasted heat I think comes from the need to heat a buffer tank. Is there a way to switch this feature off or bypass it completely? I know this would mean waiting for longer for the water to heat when having a shower, but I'm willing to live with that and use the kettle for most hot water needs.

The boiler is a 15 yr old Grant Vortex Outdoor Combi.

I had considered directly insulating the boiler, but I guess that could overheat the components and lead to speedy boiler death?!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298082#Comment_298082 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298082#Comment_298082 Fri, 07 Oct 2022 10:42:47 +0100 neelpeel
The Primary Hot Water store temperature is controlled via the “store” thermistor and control circuit board.
When reheating the Primary Hot Water store the burner will cut out when the boiler reaches 83°C (as detected by the boiler “flow” thermistor).


I've also attached the bit of the schematic that details the 'store' thermistor. I'm not particularly electrically minded...but is there maybe a way of bypassing the thermistor with a jumper or might this play havoc with the boiler function?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298192#Comment_298192 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298192#Comment_298192 Tue, 11 Oct 2022 11:44:33 +0100 neelpeel https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298193#Comment_298193 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298193#Comment_298193 Tue, 11 Oct 2022 12:37:55 +0100 Peter_in_Hungary https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298194#Comment_298194 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298194#Comment_298194 Tue, 11 Oct 2022 15:28:36 +0100 neelpeel
Edit: Meant to add...that thermostat is already set to lowest.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298204#Comment_298204 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298204#Comment_298204 Wed, 12 Oct 2022 08:58:09 +0100 Gareth J
That plus solar (PV or wet) would provide you with the majority of summertime hot water needs without the boiler. Then, I suspect, the heating side of the boiler could possibly be used as a system boiler to to up the indoor cylinder as required.

Alternatively, if you're willing to go all electric for the HW, you could get an electric shower and one or two under sink direct electric heaters.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298209#Comment_298209 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298209#Comment_298209 Wed, 12 Oct 2022 13:26:13 +0100 neelpeel - Not much space (some space for a horizontal type in the eaves but then I lose useable space).
- I'm hoping I can dump most of my spare PV into my EV.
- I think it would take a loooong time to claw back the outlay for a plumber to hook up a cylinder, shower & under counter heaters.

So for now I'm stuck with my combi but trying to reduce use and reduce any wasted heat (which I suspect is more than the actual use!). If no solutions regarding the buffer tank then I may resort to switching the HW off and on as and when required. Bit of a pain though.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298213#Comment_298213 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298213#Comment_298213 Wed, 12 Oct 2022 17:26:26 +0100 Gareth J https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298334#Comment_298334 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298334#Comment_298334 Fri, 21 Oct 2022 08:22:39 +0100 GreenPaddy
Inefficient short burning would likely consume a lot of oil compared to the heat output, soot-up the oil jets etc of the boiler, and so potentially be more costly (inefficiencies and higher maintenance costs) than anything you might possibly save in terms of lost heat.

GarethJ suggestion of a timer could work, ie. timed-off when you're out/asleep, but that risks no hot water on some occasions when you want it, so would need the boost function.

If you're up for a bit of tinkering, relocate the heatslave tank outside the boiler housing, and super insulate it. Extend the pipes a few hundred mm, so it's adjacent to the boiler, but room for insulation wrap. How much heat are you losing in the pipework delivery to your taps? More of an issue I'd guess than the heatslave tank losses.

No solutions really, but may avoid inadvertent worsening of inefficiencies.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298335#Comment_298335 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298335#Comment_298335 Fri, 21 Oct 2022 09:26:10 +0100 SimonD
If you tend to draw lots of small amounts of hot water then it's going to be more efficient to use the store, even with standing losses. If you only really use hot water for extended periods, such as shower or running a bath, then there may be some improvement.

Probably also worth doing some calcs to see how large these losses are in the grand scheme of things compared to focussing your time and effort on thermal improvements to reduce heating losses.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298336#Comment_298336 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298336#Comment_298336 Fri, 21 Oct 2022 09:44:36 +0100 Peter_in_Hungary https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298345#Comment_298345 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298345#Comment_298345 Fri, 21 Oct 2022 14:35:01 +0100 djh Posted By: Peter_in_HungaryIf you use single leaver taps always have them to the cold side unless you actually need hot/warm water. To often single levers are left in the mid position which means that any small mount of water drawn off takes some hot which will never get to the taps and so is a total waste.+1

Mixer tap handles left in the middle also drip on the tap itself and need more frequent cleaning ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298372#Comment_298372 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298372#Comment_298372 Sat, 22 Oct 2022 20:40:34 +0100 neelpeel With regards mixers, we always use full cold and even have it drummed into the kids. :-) Pretty tough when the water is about 5 degrees in the winter!
For doing dishes we generally use the kettle.
So main hot water use is for showers. Hence, my annoyance of heating the entire boiler room 24/7 just for this.

Not sure how I can calculate the loss with any degree of accuracy, but given the temperature of the little boiler room when I open the door (around 30-35 degrees I'd say) I'd say it is significant.

I think I read that the 'buffer' or 'pre-heat' water is actually within the heat exchanger, so I'm not sure how easy it would be to isolate and insulate that. I suppose the critical bit is wherever the sensor is. Got me thinking though and I'll review.
It does seem crazy that a constant pre-heat tank wouldn't be insulated in the first place. Hope the situation is improved on newer boilers!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298376#Comment_298376 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298376#Comment_298376 Sun, 23 Oct 2022 08:04:07 +0100 Peter_in_Hungary
If that can't be done if you super insulated the boiler room (if not already done) this would keep more of the lost heat in the room which should cut down the losses to the outside and indirectly cut down the losses from the boiler.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298377#Comment_298377 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298377#Comment_298377 Sun, 23 Oct 2022 09:10:49 +0100 neelpeel If I look at insulating the pre-heat tank then what is the best insulation to be quite thin and cope with high temps? Is this a job for aerogel??]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298378#Comment_298378 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298378#Comment_298378 Sun, 23 Oct 2022 09:30:55 +0100 djh Posted By: neelpeelThere is a switch on the boiler and also a fused switch adjacent to the boiler... but the boiler room is round the back of the house. I may look into routing a switch.You could just replace the fused switch with a timer model. I've used the TimeGuard ones and they seem to be fairly reliable plus they replaced one that failed without quibbling. I expect there are other brands. Gets more complicated if you want manual override as well, but perhaps there are suitable remote/wireless switches to avoid running wires.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298410#Comment_298410 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17596&Focus=298410#Comment_298410 Tue, 25 Oct 2022 06:27:37 +0100 Gareth J
Some oil boilers are incredibly full of steel. If it's in the heating season and the machine is in the house it's not so bad but I understand your predicament - it's a huge mass to heat for a few hand washes and, being integral to the machine, is hard to safely extra insulate without risking cooking other boiler components. Though having said that, I did put a bit of extra insulation around the top and sides of my system oil boiler.]]>