Pumped shower on solar system

[Mpower738]

Hi, just taken over a bungalow that has a conventional water cylinder downstairs, vented to a cold tank in the attic, and also it had a roof mounted solar hot water system with hot cylinders up there as well. A Drayton electric 3 way valve selects which cylinder system supplies the hot water for the whole house, selected by a switch in the downstairs cupboard.

Question is, can I fit a negative head shower pump in the attic after the three way valve to boost the downstairs shower, or is it essential to fit Surrey tank top outlets and take feed direct from top of cylinders???
If that is the case how will I select which tank to feed from, another Drayton 3 way valve maybe for shower pump hot feed only?

That valve would have to use same control as solar system.

Any advice appreciated

 

[Aire]

Not seen a setup like that before, do you have a few pics of the setup to help us better understand what's going on.

 

[Mpower738]

I can take some pics and post on Monday, not living there yet as it’s empty and needs re-furbishment.

 

[Mpower738]

Downstairs cylinder with hot feed from top
[automerge]1567413369[/automerge]
Roof cylinders with solar hot feed from top of closest one
[automerge]1567413412[/automerge]
Three way valve selected by switch in cupboard

 

[Aire]

Seems like a lot of stored water, how big is your property? The 3 port IMO is a silly idea as it's just going to restrict flow. If it's just a pressure boost to the shower than I'd look at the shower power booster from flowflex. You can fit them directly before the inlets to the shower so don't need to worry about where to tap off the hot supply. I believe it's a product of @Alan Wright. Wait for a response off him and he'll tell you if it's suitable or not.

 

[Mpower738]

Thanks Craig, the upstairs cylinders are only heated by the solar panels. The original installer is still in business - Sunuser

Previous tenants have said there is enough hot water through the summer months to be able to turn the gas boiler off.

Had a word with Sunuser today as the solar system needs service, and they recommend a twin coil cylinder downstairs, which would make sense, then I’ll only need one hot feed to shower pump via Surrey flange. I was thinking a 1.5 Bar Salamander positive head centrifugal would work in that setup, next to downstairs cylinder.

 

[Aire]

From my experience a twin coil cylinder is the usual method for solar hot water. If your going to buy a new cylinder and a booster pump, if your flow rate allows it, why not spend a little more now and go for an unvented?