Keeping heated water hot when not in use.

[Bury the Trash]

We are in a position of getting a fair bit of hot water periodically from a modest but successful solar thermal set up,
Generating it is easy from our panel In the sun of a day but storing overnight with minimal loss for maybe a grey er day next morning is the challenge.
How do you insulate your tank ?
any tips best stuff to insu.ate with etc, got the standard foam covered tank and some ordinary pipe lagging atm but its not enough real.y
Tia.

 

[Wesley]

Build a box around the tank. Lined with thick celotex maybe on the flat sides, something more squishing to fill up gaps between tank & celotex. Basically insulate the sh!t out of it

 

[renewablejohn]

Store at higher temperatures using thermal oil and sand box then use a heat exchanger to convert back to hot water or steam evaporator for steam output. Make sure your solar thermal setup is capable of using thermal oil instead of water as seals have to be higher temperature.

 

[Dry Rot]

During WWII house holders were encouraged to use a 'hay box' for cooking. Heat the meal in a vessel, then enclose the vessel in a box on the principles that Wesley explains, no further external heating required. It works. As described, then insulate the sh!t out of it! I do that to provide hot water for the vet to wash in when he comes, two large containers of water and a couple of bales of hay. It still works.

 

[Bury the Trash]

Ye

During WWII house holders were encouraged to use a 'hay box' for cooking. Heat the meal in a vessel, then enclose the vessel in a box on the principles that Wesley explains, no further external heating required. It works. As described, then insulate the sh!t out of it! I do that to provide hot water for the vet to wash in when he comes, two large containers of water and a couple of bales of hay. It still works.

but its not just or even so much the tank thats easy to add insulation to. its the pipes that come off it, like the ve 22mm vent pipe its a vented system. and the others they need more but are fiddly to cover well against the wall. but being metal and longish up wards they are like proper little radiators.

 

[suffolksmallholder]

Our solar thermal tank is in a small insulated room.
This is on the N elevation of the house. In winter the heat seeps through the less insulated internal walls and benefits us.
FYI, the benefit is that there is No heating upstairs. That was my original concept and it really works well.
SS

 

[Bury the Trash]

Our solar thermal tank is in a small insulated room.
This is on the N elevation of the house. In winter the heat seeps through the less insulated internal walls and benefits us.
FYI, the benefit is that there is No heating upstairs. That was my original concept and it really works well.
SS

our hot water tank in the airing cupboard is where the solar water goes to do its heating , its a twin coil tank vented as above .
th e fluffy fibre stuff will be easist to add around it i think, got a spare roll or 2 in the loft ,will sli de it behind the pipes as well i think, could do with a bigger tank but thats a lot mor emonmey thgan the 200l one we have .

 

[GEMS]

Does the tank have a vertical vent ? if so is it losing heat ? introduce a swan neck to stop vertical convection.
Other than that i agree -box it in . Fill void with insulation- those horrible foam chips stuff packaged in.......

 

[Bury the Trash]

i suppose i could fill the whole airing cupboard with them bits , from the loft through a hole in the ceiling with a big funnel then put a sign on the door warning not to open

 

[Y Fan Wen]

Space blanket type thingy?

 

[Bury the Trash]

its definatly the vent pipe from the rayburn boiler circuit losing the most ,its like a proper l;ittle metal radiator

but is it ok to put a swan neck 9as gems mentioned above0 or loop in that low down to stop the heat convection upwards .
doesnt matter so much when the rayburn is working as a bit of heat loss up there isnt noticed much. but atm when its out it s quite a lot relativly speaking as the rayburn coil is at the top of the tank where the hotest of the water is .
the tank can lose up to 10 degrees over night which is bugging me .if i can reduce that by half or so i would be happier.
the solrsr circuit is at the bottom and not an issue in this way.

 

[Lakesdigger]

its definatly the vent pipe from the rayburn boiler circuit losing the most ,its like a proper l;ittle metal radiator

but is it ok to put a swan neck 9as gems mentioned above0 or loop in that low down to stop the heat convection upwards .
doesnt matter so much when the rayburn is working as a bit of heat loss up there isnt noticed much. but atm when its out it s quite a lot relativly speaking as the rayburn coil is at the top of the tank where the hotest of the water is .
the tank can lose up to 10 degrees over night which is bugging me .if i can reduce that by half or so i would be happier.
the solrsr circuit is at the bottom and not an issue in this way.

NO do not put a swan neck in a vent pipe. Unfortunately you are finding out that more modern efficient renewable systems do not tie into old fashioned systems without some compromise

 

[Bury the Trash]

NO do not put a swan neck in a vent pipe.

point taken any impedance to free flow will be dangerous.
the exception might be to put the swan neck /loop at the very top above the water line.

Unfortunately you are finding out that more modern efficient renewable systems do not tie into old fashioned systems without some compromise

theres nothing unfortunate about it its works a treat and is providing us with the hot water we need and all off grid. when the rayburn is out. perfectly complimentary. on a daily basis with no running costs.and relativly low capital cost as ive done it all myself
i just want to reduce wastage to a minimum.as a final stage

but overall insulating that pipe plus a few others to the max will be the best to do when i get chance.

 

[Lakesdigger]

point taken any impedance to free flow will be dangerous.
the exception might be to put the swan neck /loop at the very top above the water line.

theres nothing unfortunate about it its works a treat and is providing us with the hot water we need and all off grid. when the rayburn is out. perfectly complimentary. on a daily basis with no running costs.and relativly low capital cost as ive done it all myself
i just want to reduce wastage to a minimum.as a final stage

but overall insulating that pipe plus a few others to the max will be the best to do when i get chance.

The idea with the swan neck (which can't be done anyway) is to stop circulation in the vent pipe as the heat rises and then cools and then colder water sinks back down so even if you were to do it above the water line it wouldn't help. Insulation is the only option for the vent pipe tbh.
The unfortunate bit I refer to is the fact that gravity systems do come with some efficiency losses which can't be overcome but obviously have other advantages

 

[Bury the Trash]

The idea with the swan neck (which can't be done anyway) is to stop circulation in the vent pipe as the heat rises and then cools and then colder water sinks back down so even if you were to do it above the water line it wouldn't help. Insulation is the only option for the vent pipe tbh.
The unfortunate bit I refer to is the fact that gravity systems do come with some efficiency losses which can't be overcome but obviously have other advantages

I Just thought it might stop the hot air rising through the Swan neck .


For low cost and simplicity of build for an amateur really wanted the solar circuit to be gravity run thermal convection wasn't fast enough though and I also wanted to ground mount thd panel which meant horizontal runs .
Break througn moment came when I realised j could get a 12v pump plus the fact that it didn't need to be pressurised at all so it's actually vented solar thermal system . All 12v controller and all . Works well and all off a little pv panel.

 

[suffolksmallholder]

 

[Lakesdigger]

I Just thought it might stop the hot air rising through the Swan neck .


For low cost and simplicity of build for an amateur really wanted the solar circuit to be gravity run thermal convection wasn't fast enough though and I also wanted to ground mount thd panel which meant horizontal runs .
Break througn moment came when I realised j could get a 12v pump plus the fact that it didn't need to be pressurised at all so it's actually vented solar thermal system . All 12v controller and all . Works well and all off a little pv panel.

It's not hot air rising in the vent pipe it's hot water circulating in the pipe cooling as it gets higher up (away from the heat source or stored volume of hot water if you like) and so falling back down to be replaced by more hot water. It's a very slow process but does rob heat over time as you know by the temperature drop in the cylinder (obviously the cylinder lagging will be the biggest culprit).
The main reason you'd struggle to get gravity solar working is due to the low volume of water in the panels, you need a lot more volume of water for gravity systems to work which just wouldn't work with panels as they work by concentrating a large surface area onto a very small volume of water.

 

[renewablejohn]

Are your vent pipes copper if so replace with plastic as its not as thermal conductive. Only caveat to that is output from a boiler which may get to hot and melt the plastic. That said just a couple of foot of metal pipe from the boiler is sufficient to bring the temperature down within spec of the plastic pipe.

 

[Wurzeetoo]

Thinking outside the box, you can get a large plastic conduit designed to go over refrigeration pipes. You could either use it as a mould over the pipes and fill with expanding foam, remove it, clean it with foam remover and do another section. Just don’t forget to silicone spray the inside as a release agent

or install it and pack it with loose fill insulation?

alternatively, if it’s in an airing cupboard B&Q do some recycled plastic non itchy fleece blanket, You could fill it to you’re heart’s content! Just check for rodents regularly.

 

[Lakesdigger]

Are your vent pipes copper if so replace with plastic as its not as thermal conductive. Only caveat to that is output from a boiler which may get to hot and melt the plastic. That said just a couple of foot of metal pipe from the boiler is sufficient to bring the temperature down within spec of the plastic pipe.

Deffo do not use plastic on vent pipework at all.