Thermal Solar Panels With A Combi Boiler

wookie008

Hello!

So I've recently moved into a house fitted with solar thermal panels and am trying to work out how to use them. We also have a combi boiler, so I'm wondering when I set the thermal panel to run the heating, do I have to make sure the centrel heating from the boiler isnt on?

Cheers.

Grenage

Do you have a hot water storage tank? I assume you must, if you're heating water with solar. You shouldn't need to change anything, as your boiler will only heat the water if it's below the target temperature.

Le_Kirk

Unusual to have a hot water cylinder with a combi as it usually delivers hot water on demand. Also strange to use solar panels for heating given that you probably want the heating at night when there is no sun. Maybe what you actually have are photovoltaic panels that provide electricity only and feed back into the mains using the Feed-In Tariff (FIT), in which case just use your heating normally and watch your electricity meter running backwards earning you money. Are there any user manuals with the panels, check your electricity bill for FIT.

wookie008

Le_Kirk wrote: »

Unusual to have a hot water cylinder with a combi as it usually delivers hot water on demand. Also strange to use solar panels for heating given that you probably want the heating at night when there is no sun. Maybe what you actually have are photovoltaic panels that provide electricity only and feed back into the mains using the Feed-In Tariff (FIT), in which case just use your heating normally and watch your electricity meter running backwards earning you money. Are there any user manuals with the panels, check your electricity bill for FIT.

They're definately thermal panels, we have a seperate control panel which you can set timings etc on for hot water and the heating. I think the panels were originally installed to supplement the combi. They heat the water during the day and store it in the cylinder to be used later on if that makes sense? What I want to make sure is that for hot water and heating, it prioritises the essentially free hot water from the thermal panels.

tonyh66

probably not got a combi but a heat only boiler which will heat radiators on demand, or heat your tank up if you want hot water. If the tank is already hot, the thermostat on the tank will switch the boiler off. I don't think the panels can heat the radiators directly, they will only heat the tank.

ComicGeek

tshirttan408 wrote: »

They're definately thermal panels, we have a seperate control panel which you can set timings etc on for hot water and the heating. I think the panels were originally installed to supplement the combi. They heat the water during the day and store it in the cylinder to be used later on if that makes sense? What I want to make sure is that for hot water and heating, it prioritises the essentially free hot water from the thermal panels.

There were some systems installed where the solar cylinder is fed directly into the combi boiler - so rather than having cold water piped to the boiler, it has preheated water from the cylinder which is then heated up further by the combi boiler if required. This would then provide free hot water from the thermal panels if the cylinder is hot enough. The solar panels should automatically work to heat up the cylinder, so there shouldn't be any need for time control on the hot water side - the pump will automatically operate when there is a large enough temperature difference between the panels and the cylinder.

It would be unusual and overly complicated to have the same cylinder plumbed into the space heating system as well, not least because you're unlikely to get sufficient output from the panels in winter to make any difference - it would be a waste of money to install the necessary controls etc for this. Are you sure that the separate control is not just for the combi boiler, and not for the solar panels?

Did the sellers leave any system description or schematic that you can post on here? Otherwise you may need to trace some pipework to see what feeds what. Posting photos of the controls, combi boiler and cylinder will also help.

lstar337

ComicGeek wrote: »

There were some systems installed where the solar cylinder is fed directly into the combi boiler - so rather than having cold water piped to the boiler, it has preheated water from the cylinder which is then heated up further by the combi boiler if required.

It would need to be a sealed high pressure cylinder as a combi needs mains pressure input.

Are we certain OP isn't falling into the old trap of calling the boiler a combi when it is a standard system boiler?

Combi seems to be confused with 'condensing' a lot, or I have even seen 'just anything modern looking' described as combi before.

Alex1983

I've seen combis with cyclinder usually unvented. Not common but they are about, the combi hot water would do a kitchen/ utility and the cyclinder would do bathrooms/ en suites.

I would guess they have a system boiler though.

lstar337

Alex1983 wrote: »

I've seen combis with cyclinder usually unvented. Not common but they are about, the combi hot water would do a kitchen/ utility and the cyclinder would do bathrooms/ en suites.

That's true Alex, I have seen it on the rare occasion. That has the cylinder on the output of the boiler though, where it is used just like a system boiler. The post I quoted was describing a system where the cylinder is heated via panels (during sunny periods), and then fed into the input of the combi, sort of like a solar pre-heat type arrangement.

That I have never seen!

Alex1983 wrote: »

I would guess they have a system boiler though.

I think that is the case. Hopefully the OP can confirm.

Alex1983

I wouldn't say there definitely not made like that but I can't see it, for that system to work surely the cold water pipework would have to go through the solar panel or some sort of heat exchanger to transfer the heat.

lstar337

Alex1983 wrote: »

I wouldn't say there definitely not made like that but I can't see it, for that system to work surely the cold water pipework would have to go through the solar panel or some sort of heat exchanger to transfer the heat.

Yeah, the panels are a closed system and only heat the water in the tank through a heat exchanger. The combi needs mains pressure water to function though, and high pressure water tanks are a PITA at the best of times.

Not sure how a combi would react to a warm feed on the inlet either.