Solar Water Heating - please advise

[ziggy1979]

Hi Everyone!

I'm not sure if this is the right place for this post but i think it is!

We are thinking of investing in a solar water heating system and had a few questions:

1. Can a shower pump run off them directly as they can off a hot water cylinder, provided the cold water is in a tank and not mains?

2. How many "litres pay day" would a family of 4 need? Initially i thought about showering, but then theres sinks, baths, etc.

3. Can they be connected to dishwashers and washing machines like you can do with a combi boiler?

4. Can they be used as a "wet underfloor heating" system for one room alone (in the winter and it would be the hallway).

I look forward to hearing from you.

Thanks a lot!!!

 

[Agile]

Solar power only provides some hot water for part of the year and most of the water for the summer months.

You cannot use solar for heating in any normal situation, partly you cannot store enough heat and that there is insignificant solar power when you would want heating.

If you had an open vented cylinder you can use the hot water in the same way as any other system.

You need about 1m² of panel or tubes per person. You need a cylinder of about 50 li plus 50 li per person. Its better to have a slightly larged cylinder as they cost little more and some storage overnight will help if the next day is cloudy.

Tony

 

[ziggy1979]

Hi Agile

Thanks a lot for your response. Please note that the solar heating system would be installed in the south of spain which would hopefully have better weather in winter than over here!

With an open vented cylinder, would the solar heated water be used to indirectly heat the (cold) water in the cylinder or would you suggest that the (solar) heated water go directly into the hot water cylinder?

Presumably the latter can be backed up by an imersion heater for the cloudier days?

Also, I've seen a system that claims to heat 1000 litres per day. Would this suffice or is it overkill?

Thanks again for all your help!

 

[Agile]

If you dont give full details in your posting then you dont get the right answer and waste our time.

I told you what volume of hot water you ideally need per person.

The weather is better but not that much better in the winter.

In the UK we use complicated high tech solar systems at considerable cost.

In most Med countries they use a very simple and cheap system. A circular tank is raised about 1m above the roof and a directly connected panel about 1.5m high and 0.8m side is fitted beside the tank and heats by gravity convection. Very simple and very cheap.

Tony

 

[ziggy1979]

Tony

Thanks for the reply and so sorry for having wasted your time - i wasnt aware that the technology used in Spain was different to that used here.

Given that the system you dscribe for abroad is a cheaper system, does that mean that using the type of system used in the UK abroad would be more efficient/heat more water than the cheaper systems you described (i.e. are they any "better" or simply better suited to this climate)?

Also, with the cheaper ones, you mention that the water comes down by gravity as the tank is raised. Does this mean that shower pumps, etc can be plumbed straight from this tank?

I have also read about air to water heat pumps. Are these any "better" at heating water than the solar systems?

Thank you very much for all your help!

 

[Agile]

The simple Med system costs nothing to run and only a few pesetas to buy and fit.

The UK system is very expensive perhaps about £4000 and has running costs.

The Air 2 Water costs about £4k-£8k perhaps and costs a lot to run.

There is no point heating masses of hot water. You can only use the 50 li/person.

In the summer in Spain there is too much heat which is why their simple system can work so well as it does not need expensive insulation or complicated controls.

Tony

 

[Nordio]

The Air 2 Water costs about £4k-£8k perhaps and costs a lot to run.

A three KW Activair air/water heat pump costs about £700.
For anyone savvy with diy it could be installed for less than £1000.

 

[Agile]

I agree that there are some cheap ones about but the reliability of many of these systems seems poor and the warrantee period seems very short compared with the cost.

I suppose I am only accustomed to seeing the costs of the systems provided through the boiler manufacturers like Viessmann and Worcester.

But that is quite expensive and has operating costs whereas a cheap solar is free to use. Although the solar will only work on bright days and the heat pump whenever the temperature is well above freezing.

Tony

 

[DeltaT]

In Southern Spain, you'd be mad fitting anything other than solar to heat water!! I've seen both standard roof mounted panels & tank above panel systems there.