Information for old solar heating system

[CaptainC]

Hello everyone,

We've just moved to a new (to us) house and inherited a solar hot water system that, from the small amount of docs we have, looks to be a good 30 years old at least. So, looking for some good sites/information that I can read up on to understand how this thing operates before I start tinkering with anything.

What I can see from a brief look at the weekend, the set up is:
- Seemingly two water tanks, and expansion vessel, in the loft
- Hot water tank in bathroom cupboard
- A 'Frepar RESOL E1' (switch/controller?) linked to some kWh counter, a fused spur, and a switch labelled 'solar' / 'pre heat'
- An equally venerable gas boiler down in the kitchen
- Four solar panels on roof, with pipework down to the tanks in the loft.

Any resources that people could point me to would be very much appreciated; the biggest reason at the moment is that the hot water isn't all that hot, even when turned on at the boiler (and hot feed out seems OK), so looking for pointers on different parameters to try.

Thanks all!

 

[OzSolar]

Bumping your post in hopes someone can help. I'm familiar with SHW in the states but none of what you've mentioned rings a bell to me. There's a specific sub forum for SHW so you might post this there as well.

 

[JBertok]

Most solar hot water systems have a differential temperature controller that operates a small low-wattage recirculation pump, typically a Grundfos or similar. The differential controller's only job is to run the pump when the collectors are hotter than the tank(s), circulating water through the collectors and tank(s). The collectors on the roof should have a thermostatic and pressure relief assembly at the high point that looks sort of like a water pressure regulator, and will be made from black thermoplastic, brass, or even stainless steel. This is a safety piece you'll want to verify hasn't been omitted over the years; they can be a nuisance maintenance item due to leaking.
Old systems have no heat exchanger, so the collectors, pump, and tanks) are at service pressure - the same water circulating though it is what eventually comes out your tap. The tank(s) is/are probably similar to (or even exactly like) an electric water heater without the elements. You mentioned your hot water is not very hot. I've always seen solar water heating installed as a preheater to a conventional water heater, and that water heater becomes the temperature regulator for your hot water. Today, a solar hot water system would be a preheater to a tankless electric/gas/propane water heater. (Electric tankless water heaters are a fraction of the cost of gas ones and are more often rated compatible with recirculation or pre-heated supply.) Maybe there's no conventional water heater, or maybe it's non-functional?
The tank under the sink in the bathroom seems unrelated. That could just be an electric demand heater which would be likely if that's a bathroom far from where the tanks are.
Are you off-grid with this home?

 

[CaptainC]

Many thanks for taking the time to reply, we're in the UK (on grid) so quite possibly a different ball game like our electrics

I will try to get in the loft over the weekend and map out a diagram of what I can see, which will hopefully be a better description of what we currently have.

 

[Daddy Tanuki]

Many thanks for taking the time to reply, we're in the UK (on grid) so quite possibly a different ball game like our electrics

I will try to get in the loft over the weekend and map out a diagram of what I can see, which will hopefully be a better description of what we currently have.

Thats the attitude! never give up. one of the things I admire about GB that most Americans (US) absorbed from our cousins.