Tanks for solar heated water?

peaches79

Hi,

I'm currently building a house and want to know what type / size of water tank to put in.

In a few years I want to add a solar panel or two to heat the water.

The house has underfloor heating (600 square foot) and has 3 bathrooms, 1 with an oversized bath. 2m long x 1m wide x 1m deep.

What size / make of tank should I put in to allow the easiest installation of the solar panels.

Cheers,
Peaches.

Oldtree

Thats a big bath, where did you get it?

normal tanks for a household would be between 300-500l, but your bath is a bit bigger than that. You need to figure tha amount of hot water you need to fill the bath, excluding the cold water to cool it down to an appropiate temp. Then add the normal daily hot water needs of the household and you have the size of tank you need if you take regular baths. you are going to need quite a few solar panels to fill that bath.

This tank will be very costly to heat with oil or electric, a multi fuel backboiler stove would be very helpful in the winter.

I'm going for a 300-500l double lagged copper cylinder in my build, as I know a single lag will keep the water hot for up to a day.

I've found a copper cylinder manufacturer in (Cork i think) on the internet that will put in the extra coils I need.

Gurgle

Oldtree wrote:

I've found a copper cylinder manufacturer in (Cork i think) on the internet that will put in the extra coils I need.

Can you give us a hint about who they are and how much the tank costs?

maniac101

OP, the size of the HW tank is best determined by looking the number of occupants in the house rather than on the no. of taps etc. I think 50l per person per day is the rule of thumb. A 200l tank is often sufficient for small families. (Having said that, if you're all planning to wash in that giant 2000l bath, then 200l won't go far unless you all get in together!;) ) You could go for something bigger but as oldtree says, you're going to need more solar panels.

You'll need to use a solar cylinder. This is a tall narrow tank with two water coils, one coming from the central heating, and one lower down coming from the solar circuit. In the typical setup, the water from the solar panels doesn't flow into the central heating circuit so it wouldn't heat your underfloor system. I'm thinking that you won't get much useful heat if you fed into the central heating circuit directly, bearing in mind that the panels are least efficient in Winter when you need the underfloor heating the most.

My advice would be to put in the complete system from the word go, rather than waiting a few years. It'll be cheaper in the long run and you can take advantage of the SEI grants scheme (which may no longer be there in a couple of years). In our case, we abandoned the idea of solar panels in our house due to costs, as the house was already built and the civil work involved in making space for the cylinder made it unviable and an awful lot of hassle. But for a new build it will definitely be worth the investment.

Oldtree

Lycris Byrne Ltd copper and steel cylinders Fairgreen Road, Bray, Co Wicklow. Tel: +353 1 286 3794. is the company I found on the internet. The main reason I want to get my tank manufactured is that I want 3 circular coils at the base of the tank, one for solar, one for stove backboiler and one spare for the future, hot water rises after all. also one normal electric element and also space for another element (wind connection). to kind of future proof the tank and gives me all the options i would need. it may seem a bit of an overkill, but I will say that the ESb will not be able to provide electricity demand at peak times within two years. A photovoltake panel will run the solar pump for hot water in the summer and a stove, with a good rise to the tank will give space heating (albeit via open doors) and hot water in the winter.

Oldtree

oops forgot inet addy:

www.lycrisbyrne.com

I would stress thet I do not work for this company nor have I purchased one of their products yet, but they seem to be up on their subject.

Oldtree

having said all that i've just gone to have a look at how much insulation is on my current tank and noticed a sticker on the back saying

Austom (Galway) ltd, mfr of copper cylinders.

Might give them a ring to see if they can make my tank design at a reasonable cost, (supporting local jobs)!!!

bushy...

Maybe think about recycling greywater for flushing toilets etc ?

djmc

if it were me I would go a few quid extra and go for a twin coil stainless steel
It should last longer than the house and you could have mains pressure water for power showers without the need for pumps

ircoha

djmc wrote:

if it were me I would go a few quid extra and go for a twin coil stainless steel
It should last longer than the house and you could have mains pressure water for power showers without the need for pumps

Just asking here so dont get jumpy like one of the mods did with me elsewhere today.

AFAIK, the current regs allow only one outlet from the rising main which is normally the cold in the kitchen so is what is being proposed here legal.

In relation to the bath, assuming it is half full of water it will require 1000 litres to fill it so I hope the floor is up to it.

smdweb

Check Out www.solarhouse.ie they do a lot of items for solar heating, the products page has a full listing of items... hopefully that might help you.

Rovi

ircoha wrote:

In relation to the bath, assuming it is half full of water it will require 1000 litres to fill it so I hope the floor is up to it.

I was just thinking that; that 1000 litres of water will weigh 1 tonne, the full of the bath (2000l) will obviously be 2 tonnes. Plus the weight of the bath itself and all the attached plumbing etc, I hope it's downstairs

Degsy

Why would ANYBODY want a bath three feet deep,six feet long and a yard wide?Is the house being rented out to giants when(if) its finished?

Degsy

Degsy wrote: »

Why would ANYBODY want a bath three feet deep,six feet long and a yard wide?Is the house being rented out to giants when(if) its finished?

swimming pool for the children!!

Having said that, there are a large number of "hot tubs" out there that are bigger.

If the water is being heated by solar, then there is no real waste of energy.

Degsy

Deleted User wrote: »

swimming pool for the children!!

Having said that, there are a large number of "hot tubs" out there that are bigger.

If the water is being heated by solar, then there is no real waste of energy.

Pretentious crap more like.Anyway,you'd need more than one solar panel to heat that,especially during the winter.