Putting a cylinder jacket on a foam 'insulated' tank

twopenny

The house I've moved into has hardly been used since being  built 20yrs ago so things have hardly been used but they're not new.

I'm finding the hot water goes cold quickly, either after running hot through the taps a few minutes later it comes through cold again so I'm trying to trace any HW pipes and insulate them.

My main concern is that the foam covered hot water tank doesn't keep the water hot for long. And I can open the airing cupboard and let out tons of heat.

Is it OK to put a cylinder jacket on an insulated tank? Or could it cause problems and unbalance a system?

Simplish question but I don't want to cause more trouble when trying to improve things so grateful if anyone knows if this is fine to do. Thanks.

grumbler

IMO it's perfectly OK

nofoollikeold

1. Its fine to add further insulation, but don't cover the top of any immersion heater fitted.
2. If it runs cold after only a few minutes (after allowing a while for cooling water to empty from the pipes) then it could be a mixer tap or Thermostatic Mixing Valve (TMV) letting cold water into the hot pipework.  

daivid

Can't see a problem, before switching to a combi boiler my parents had 3 insulation jackets covering the immersion heater, this set up caused no issues for over 20years. If there are controls on the tank I would leave those uncovered (by lining up the slits in the jacket).

twopenny

Thank you for the reassuarance. I can't get a jacket at the mo it seems but can wrap it in a sleeping bag.

I'll take care not to do the top.

Interesting about the mixer tap - the builders didn't run to TMV's in this build. I figured I'd trace the hot pipes somehow as they're easy to insulate. They run up the walls and through the loft but it's worth a try.

I'll ask the plumber when he comes to do the bathroom. He said end October - but he didn't specify a year. So I welcome any ideas.

I miss my old house plumbing. Oddly it was more efficient than this relatively new bungalow.

Mickey666

I can’t a problem with adding insulation to a hot water tank.  I’m pretty sure that no installation RELIES on any heat loss from the tank, so helping to prevent it won’t cause a problem.

However, In terms of the airing cupboard being hot, I’d look for bare copper hot water pipes first - they can act as quite effective ‘radiators’ in their own right, especially in an enclosed space.

twopenny

Daivid I missed that post - yes, my old house, bathroom east corner with two outside walls I used old jackets  x2 and a sleeping bag so it almost filled the cupboard.

But I had hot water all day from once heating. But it was just the copper cylinder. I expected more from the 'nowadays they're all insulated' tank. No probs with toilet chain flushed loo, hardly needed cleaning and only ever cost me £8 for a new washer after 60yrs.

So this is all a learning curve.

twopenny

Thanks Mickey. Yes, it's a bonus on very cold days to open the airing cupboard to supplement the heat in this little place.

Always look on the bright side

FreeBear

twopenny said: I figured I'd trace the hot pipes somehow as they're easy to insulate. They run up the walls and through the loft

You'll want to get as much insulation as you can on the pipes in the loft. The cheap stuff from Screwfix is only around 13mm thick. OK for pipes inside the house, but not really good enough in the loft. Go for 25mm thick lagging, and then loosely wrap loft insulation around for a belt & braces approach.

I've got two jackets on my HW cylinder, and will be boxing it in with some spare Celotex insulation boards at some point. No such thing as too much insulation.

Jeepers_Creepers

As far as I can see, there are potentially two issues here, and I'm not sure which one is more relevant to your problem.

The first is heat loss from the hot water supply pipes to your taps. From your first post, I gathered that this was the problem? Ie, you run a hot tap, the delivered water is initially cold and it takes a good few seconds before hot water is delivered, you shut the tap off and then turn it back on 5 minutes later - hey presto, water is coldish again for a good number of seconds before running hot? In which case the cause is heat loss from the delivery pipe. 

Solutions: lag! Try and shorten the pipe route. Replace pipes with plastic - and lag these too.

Or - the other issue - the water stored in your hot tank is losing heat excessively fast? If it's simply down to lack of insulation on the cylinder, then chuck on an aftermarket cylinder jacket (and, personally, I wouldn't be concerned about covering the immersion heater head or the cylinder stat - these things are already sitting at well over 60oC, or some systems a lot more than that, so ain't going to get any hotter with a jacket over them). Also, as said before, lag any copper pipes in there. 

Before blaming it all on heat 'loss', tho', I wonder if perhaps your new cylinder is smaller capacity than the one in your old house, or is not being heated up to such a high temp as t'old, or is being heated at a different level - eg an immersion will often only heat the top third of a cylinder? 

Apodemus

Jeepers_Creepers said:

Before blaming it all on heat 'loss', tho', I wonder if perhaps your new cylinder is smaller capacity than the one in your old house, or is not being heated up to such a high temp as t'old, or is being heated at a different level - eg an immersion will often only heat the top third of a cylinder? 

Depending on the type of installation there is also an outside chance that the motorised valve to the cylinder is remaining open and that on shut-down, the CH pump over-run is continuing to route hot-water from the tank through the CH radiators until the whole system comes down to a lower temperature.