need some newbie advice on best hw tank

[cypher007]

going to have the hot water tank replaced and need advice on the best solution.

scenario:

we will have 4kw of solar pv to heat hot water in the summer, using a redirect controller and immersion heaters.
I would like a mains water fed system to keep things simple and the shower strong.
we have an old gas boiler which I think we will use until the thing breaks.
the house is 1967 4 bed (was 3 bed then extended). we use quite a lot of hot water, old house had 90l and we kept having to turn on the boiler for hw maybe 3 times a day.

solution:

indirect unvented tank about 200-210l? which tank?

also would two immersion heaters be better, I could have them staggered.

 

[lame plumber]

would have been better off going for solar hw system to get free hw altogether imho. get a local green expert in to advice you as there are several things you need to get right or life will be a pain in the long term

 

[cypher007]

I thought it would be a case of just buy the tank and go, like with our old house.

ive been looking at this sort of thing:

 

[Dotty]

Not at all. Lots of stuff to take into consideration. The most important of which is who is fitting your unvented cylinder?

 

[AWheating]

If your existing system is old it will most likely need upgrading in some way. Is it fully pumped?, what controls does it have? Does the boiler have an over heat cutout?

Dose your cold water supply provide adequate flow and pressure or will it need upgrading or a booster set? Where will you discharge run?

Plenty of things to consider