What size system for 2 adults and daughter

Mad Benny

I have received three quotes from reputable evacuated tube solar systems providers.

Two of the installers recommended a 200l system with 2 square metres of tubes.

The third recommended a 300l system with 3 square metres of tubes.

It is unlikely that there will be more than three people living in the house while we are there. The installer who recommended a 300l system with 3 square metres of tubes said that for the sake of €600 we would better going with the larger system.

We use the bath about twice a week. Apart from that it's three showers each morning.

I've heard over the years - the rule of thumb is 1 metre squared per person.

Any advice?

BryanF

Mad Benny wrote: »

I have received three quotes from reputable evacuated tube solar systems providers.

Two of the installers recommended a 200l system with 2 square metres of tubes.

The third recommended a 300l system with 3 square metres of tubes.

It is unlikely that there will be more than three people living in the house while we are there. The installer who recommended a 300l system with 3 square metres of tubes said that for the sake of €600 we would better going with the larger system.

We use the bath about twice a week. Apart from that it's three showers each morning.

I've heard over the years - the rule of thumb is 1 metre squared per person.

Any advice?

benny as you said, rule of thumb is 1msq per person up to 6 people. so 3msq and with two girls in the house (+ the odd visitor) imho go for the 300l tank:), if this is a retro-fit get the guys to be extra carefully where and how they lay and fix the pipe work in the attic, ensure continuously insulated but easily accessible pipe runs. its a good time to ensure all your attic pipework and water tanks are well insulated also.

championc

For effective heat gain, you need 30 tubes for 180L, 50 tubes for 300L or whatever but keep this ratio of tubes to L. So your main decision is really as to how big a store you want / have space for.


C

quentingargan

championc wrote: »

For effective heat gain, you need 30 tubes for 180L, 50 tubes for 300L or whatever but keep this ratio of tubes to L. So your main decision is really as to how big a store you want / have space for.


C

I agree, but many systems that do not use a heat dump suggest a lower ratio of tubes to cylinder size. This is fine in mid-summer, but reduces output on the fringes of the season. It is done to prevent the system going into stagnation, though of course this will still happen during holidays or at times when hot water is not being used.

I think I recall from other threads that you have a system in which the tube has an internal shut-off valve rather than a heat dump, but still installers using this system generally recommend a lower ratio of tubes to storage volume.

For a family of three with occasional baths, a 200L system is all you need. The "norm" for water consumption is generally accepted to be about 40L per person per day. 200L gives you a bit of a buffer for days like today!