Limited space hot water system suggestions?

You can get them made to size, but unfortunately you can't fit a quart into a pint pot.....

In case that wasn't clear enough... let's do some scary multiplication, in scary units called "decimeters". There's 10 dm in one m (hence 10cm and 100mm in one dm). And a cubic dm is (to all reasonable purposes) a litre. So the outside space here is 5 x 6 x 20 dm, giving a total cubic capacity of 600dm or 600l - so the tank'd have to take a quarter of the gross volume, more like a third of the internal volume once you've got cupboard doors, sides, and (oh) access space for the boiler.

If you get a custom-made rectangular tank, the biggest cross-section it could reasonably take would be say 4dm wide x 5dm deep, leaving sthg under 10cm of access space for pipework around two of its four sides, and covering it with superhypercelotex to get maximum insulation for minimum thickness. To get your 150l with a cross-section of 20 sq dm, you need a height of 7.5 dm - more like 9-10 dm once you allow for more realistic access around it. That's half your height spent on the tank. Can you fit the boiler into the remaining 1m of height? Sounds at best expensive, cramped, and hot.

I think you'll have to settle for a combi, or find space for a tank somewhere else!

That's the chink AIUI in this argument. The only tanks I've seen in this shape are made of steel. Even the ones which look rectangular in the pre-plumbed units popular in 70's flats (Harcopak etc.) actually have cylinders inside a box of foam insulation.

You could probably get a standard cylinder in if you carve off the insulation at the sides, a bit of a pig to fit though. In my own house I fitted a 375mm+insulation diameter cylinder and with the modern fast recovery coil it can produce a bath full every 15 mins.

Do you have details of who makes this cylinder Ed?

Thanks! Mark.

It's not the heating load that governs the size of the boiler but the dhw load, or rather the reheat time from last use of dhw, or if you go for a combi (god forbid) the poor flow of the dhw that governs that you get the biggest combi you kan find and even then you will still get a nasty surprise when swmbo turns on the hot water faucet in the kitchen when you're taking a not so hot shower any more...

No you need to store the heat between the uses, ie a thermal store, mine is

This is the store that is currently heated with a single 3kWh immersion heater with the thermostat set to 60 degrees celcius...

/Morten

I simply asked for it my regular plumber's merchant, it came in within 2 days.

The unit was likely made by IMI.

I'll ask if I remember who the supplier/maker is next time I call at the shop. It may well be that the merchant simply uses a wholesaler who hole a greater stock range.