Pressurised DHW or not

[oldbutnotdead]

Fitting out the House of Pain and have hit a wee problem. The roof is twin ridge and quite low pitch so there's not much headroom up there- water level in the hot water header tank is at most 2m above where the upstairs shower heads will be (showers etc not fitted yet) which I suspect will make for a disappointing shower experience

Currently the heat source (water and radiators) is a woodburner (which, as I understand the regs, precludes pressurised cylinders). Budget won't run to a thermal store big enough to be any use- or rather it will but the payback time is immense and there are some structural implications which aren't going to be cheap.

Question- will a shower pump work well enough (and quietly enough) in these circs or will I regret not biting the bullet now and switching to gas as a heat source (so I can have mains pressure hot water as well as the convenience)?

Mains water pressure is good, 25l/minute at ground level. Most of the house is a building site at the mo so no real disruption to life, mains gas is available.

Ta

 

[bernardgreen]

I had a very similar situation with the DHW in my cottage, joists unable to carry the weight of a tank.

I solved it with a bespoke vented cylinder with a second coil at the top to heat mains pressure water for the shower, taps in bath and basins fed with low head water from the cylinder ( no splashing out of basins ) .

The 900 x 450 cylinder cost £207 delivered ( plus VAT ) in 2011 With hind sight I would have chosen a larger cylinder to cater for visitor's prolonged showers.

 

[oldbutnotdead]

@bernardgreen interesting and well worth a look, ta. Price will probably have doubled since then but still not unreasonable. Cylinder size I'm looking at 250 litre ish (2 bathrooms, 4 bedrooms)
One other side issue I've got- the cylinder is a reasonable distance from the 2nd shower (about 16 metres as the pipes will run) so I've plumbed it with a secondary return (if the runoff time is excessive then I'll stick one of those £100 DHW circulating pumps that someone on here mentioned a while ago in the feed). Which of course won't work with the heat exchanger sketch (and to be fair wouldn't have worked with my original thermal store plan with plate heat exchanger). Sometimes having a blank piece of paper to work with is worse than having an existing working system.....

Amend- just done the sums again, 16m of 15mm only holds 2.3 litres so runoff time shouldn't be excessive at mains pressure. I may be overthinking this, might knock up a test rig with some gash plastic and see what happens. Ta again

 

[flameport]

a woodburner (which, as I understand the regs, precludes pressurised cylinders).

It can't be connected directly as with a normal boiler, but there are ways of using a solid fuel appliance with an unvented cylinder.

 

[bernardgreen]

Cylinder size I'm looking at 250 litre ish (2 bathrooms, 4 bedrooms)

The second coil does reduce the amount of water in the cylinder, worth bearing in mind when sizing it.

but there are ways of using a solid fuel appliance with an unvented cylinder.

True but the complexity of the safety system does make a vented system less expensive and easier to maintain. A storage tank of cold water is essential if heat from the solid fuel source has to be dumped while the fire is being drawn ( put out )

 

[Dan Robinson]

Have a 300 litre thermal store with a 100kw plate sitting in my lock up looking for a home. Has lots of tappings. Even a dedicated solar coil.


Been looking for a new home for a while.


PM me with your budget if you're interested.