Limited space hot water system suggestions?

[mark]

Hi, I'm trying to find a hot water system that will fit into a cabinet whose outside dimensions are 500mm wide, by about

2m high, 600mm deep.

I can find plenty of condensing gas boilers to fit, but I'm having a lot of trouble finding a hot water cylinder (unvented preferably)of about 400mm diameter.

I've looked at thermal store systems as well, but they are also a tad too wide. Range have a 350mm one, but it's a rediculous 1750mm high, no room for the boiler then.

I think to fill a reasonable size bath I'll need about 150L capacity.

Can anybody suggest something?

Cheers, Mark.

[Andy Hall]

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

[Stefek Zaba]

[ ... ]

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!

[Ed Sirett]

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.

375x900 is about 100 litres and should be adequate for most homes.

[mark]

Do you have details of who makes this cylinder Ed?

Thanks! Mark.

[Morten]

16kW worth of heating for a 80m2 flat, that's alot, I'm currently running my whole house (a 3 bed semi) on a single 3kW immersion heater in my thermal store. I turned it on yesterday just to se if it would cope with the load and it has done so far (the boiler hasn't come on since I turned on the immersion heater).

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

270 l and will store arround 12.5 kWh with a store temperature delta of arround 40 degrees celcius (T max = 85 degrees celcius and Tmin = 45 degrees celcius)...

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

/Morten

[Ed Sirett]

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.