Insulating a water tank

[thomp1983]

Hi all,

My sisters just moved into a terraced house and is having problems with the heating.

The house has a baxi back boiler behind a has fire, and a water tank in the loft.

Most of the rads are single panel units with 10mm pipework.

She has problems with getting a use able amount of hot water, if she puts the immersion heater on she can get enough hot water for half a bath, the fire doesn't seem to heat the water much.


I've had a look in the loft, there's some insulation between the rafters but as shown there's nothing around the tank or pipework so I suspect most of the heat trying to heat the water is going straight out the roof.

What's the best way to insulate the tank? I'm thinking maybe a few sheets of 100mm celotex to form a box around it and foil tape all the joins, the foam tubes for the pipes?

Thanks
Chris

 

[stem]

The same tanks are used by both the immersion and the boiler. So if insulation was the problem it would effect both the same.

It's a while since I saw one of these. perhaps someone more familiar with them will be along shortly and confirm, but I seem to remember the outer tank only contains cold water and the bigger one is insulated inside the casing. The outer one even though it only has cold water in should still be insulated to protect it from freezing.

Having a back boiler makes it sound like an antiquated system, so it could be that the hot water is heated by natural circulation, i.e. hot water rises cooler water falls, this is known as gravity circulation. However the central heating will have a pump, which being more powerful pumps the majority of hot water around the radiators and reduces what is available for the much less effective gravity circulation, which is notoriously slow at the best of times.

Try switching the central heating off for 2 hours and leave the hot water on, if the hot water is good then, then that indicates the problem may be with the heating system.

From what you have said I suspect that the heating system is well past its sell by date. Back boilers are terribly inefficient 40% of the heat goes up the chimney and if does have gravity circulation of hot water then conversion to a fully pumped system would be the way to improve it.

 

[Exedon]

That's a elson tank it is insulated with fiberglass under the hardboard cover.
Standard stuff in 70s coupled to a baxi Bermuda boiler did hundreds in council house conversions.

 

[thomp1983]

It is an old system, the landlady has said she'll replace it with a new boiler but it won't be until into the new year, probably February onwards.

In the meantime my sisters stuck with 2 young kids trying to make the best of it, I'll suggest she sets the timers to heat the water early morning say between 5 and 7 and the have the heating come on ready for getting up and see if that works any better for her.

There were no instructions with any of it, does the gas fire need to be lit to heat the water without using the electric immersion heater? Or should the boiler heat the water if its switched on at the control panel?

 

[conny]

If you have a heating boiler, as well as the back boiler, it would help to post a few details about make and model etc. A few photo's can also help a great deal.
The tanks in the loft need to be well insulated to prevent them freezing. They do not contain hot water, just cold water which is usually used to feed any upstairs cold taps and toilet cisterns. They also need an insulated lid to prevent dust and dirt contaminating the water, (this is the water you use to brush your teeth with). Any insulation actually UNDER the tank needs to be removed to allow 'house heat' to reach the underside and help prevent potential freezing. Taking the side insulation right down to between the rafters it is sitting on, so it touches the bedroom ceilings will stop any heat escaping into the main area of the loft.
Just had a thought. If there is a gas fire instead of a coal fire, then I think the back boiler may well be redundant as they used to be heated from the heat of the coal fire. If this is the case, then any problems may well stem from the type of boiler you have.
Therefore, pictures and make/model details will vastly help.

 

[thomp1983]

The only boiler is the baxi back boiler behind the gas fire, this seems to do the hot water and the central heating but she has no information on how it all works and the landlady has just bought the house so knows nothing about it either.

So is it worth insulating the tank or not? I know the pipes definitely are as there exposed in the freezing cold loft space

 

[stem]

They do not contain hot water

I'm fairly certain the back one does contain the hot water and as @Exedon said it is insulated under the cover. But these are so old I've only seen one once and that was when it was taken out about 25 years ago. The pipes to it should definitely be insulated though. If I'm correct two of them are the flow and return from the boiler. If so they will get hot when the boiler is on so easy to tell. The outer cold water tank may have some insulation, difficult to tell in the photo. But if not, some insulation would prevent it freezing.

I seem to think the cold tank feeds both the boiler and domestic hot water system. If so it wouldn't be possible to connect a new boiler to this, existing system the whole thing would need replacing and the sooner the better, this set up would be incredibly inefficient. I would expect that the EPC provided when the property was rented out would be low to reflect it.

 

[thomp1983]

Epc was an E rating and the landlady is talking about a new combi boiler with all new rads

 

[stem]

E is the minimum that can be legally rented out at the moment, but is expected to increase to a C in 2025, although that may only legally apply to new lets to start with. Hopefully the landlady will expedite the new heating system sooner rather than later.