solar thermal just for hot water.

[gjcone44]

hi i am a spark, who has fitted solar pv on south facing roof.i am now looking at getting solar thermal, to supply my hot water ( just for upstairs, one shower and 2 sinks)have got combi boiler worcester, 30cdi. but dont want to get involved with that. have 2x2mts, on south facing roof, but also have a hip roof facing west, would like to fit panels / tubes, on both have plenty of room in loft for 250l tank, question is would you fit to separate systems, to feed a twin coil tank or would it be better to link the 2 together, and supply single coil tank, the solar experts advice would be appreciated :25:

 

[Howsie]

I wouldn't bother to be honest. You'll never recoup the cost of the install on one shower and two basins.

 

[gjcone44]

thanks for reply howsie, would be installing most of the stuff myself and would of thought it would help just through the summer at least, my wife loves to shower for over 20mins and it winds me up knowing the boiler is running for that time, and she will have the heating on in summer? she was born in south africa !!

 

[Howsie]

Fair enough. The woman usually wins.

Wrt, solar thermal and unvented. You can't touch either of those without the appropriate certs...

 

[Nostrum]

Just fit a cylinder and dump the p.v into it through an immersun and immersion or similar. Far cheaper and you'll utilise all the free leccy from the p.v.

 

[gjcone44]

thanks lads i am going to fit a immersun, to back up the solar tank, just want to know if it is better to have 2 solar coils in tank and have the south facing in the bottom coil, and the west in the top coil? or would you link them together? and just have the single coil.?

 

[Howsie]

I'm out.

 

[eaton]

Just have one south facing, but if your going immersun I'd not bother with thermal at all

 

[eaton]

Just re reading your posts I strongly advise you get someone in who knows what there doing, you haven't grasped a twin coil cylinder or how many tubes/panels a cylinder can take, inc stagnation etc

 

[gjcone44]

thanks for your replys eaton, i have been reading all the posts on solar thermal, and trying to work out ,how good it realy is.? is 30 tubes south facing ok for a 200l tank, i can only fit a 24 tube on front south facing, just looking at supplying upstairs shower and 2 basins. enough for 2 -3 showers a day. for stagnation would pipe for heat dump.

 

[Howsie]

thanks for your replys eaton, i have been reading all the posts on solar thermal, and trying to work out ,how good it realy is.? is 30 tubes south facing ok for a 200l tank, i can only fit a 24 tube on front south facing, just looking at supplying upstairs shower and 2 basins. enough for 2 -3 showers a day. for stagnation would pipe for heat dump.

Open your ears.

 

[gjcone44]

i thought you were out?

 

[eaton]

30 tubes would be fine on that cylinder and shouldn't need heat dump. But depends on model of tube as if your fitting kloben/kingspan type 30 will boil. Can't advise enough getting a qualified experienced person in

 

[happyflyer]

I'm out.

Howsie, don't do the OUT thing, now will will never get 148 thanked out of 148 posts, just a thought😛rrr:

 

[Jimbob]

I would probably get a twin coil tank, use the bottom coil for the solar tubes, and connect the top coil to the boiler Via an S plan. I would then feed all the hot outlets from the cylinder and valve off the hot supply from the combi and only use it if you ever need it.

If your combi is compatible, You could alternatively use a cylinder to preheat the water into a combi, but that's not a great way of doing it.

All this naturally needs to be completed by a qualified engineer with solar certification and unvented tickets. If you supply all the kit and get a mate in to do the plumbing it should work out quite cost effective.

 

[Gray0689]

30 tubes would be fine on that cylinder and shouldn't need heat dump. But depends on model of tube as if your fitting kloben/kingspan type 30 will boil. Can't advise enough getting a qualified experienced person in

30 tubes on 200l
Rule of thumb is for every 100l 10 tubes

 

[eaton]

I always put 20 tubes on 150-180l, 25-30 on 200.

Were still missing point, if your using immersun scrap the thermal full stop

 

[Gray0689]

I always put 20 tubes on 150-180l, 25-30 on 200.

Were still missing point, if your using immersun scrap the thermal full stop

To much if using kingspan

 

[eaton]

Yep but I won't fit kingspan. As already stated be careful with kingspan and kloben. On 200l cylinder with kloben I'd go 12 tubes max

 

[gjcone44]

thanks lads i am not going for the immersun, only 2k of pv on roof, wifes in most of the day works from home. not getting involved with boiler, so looking at 24 tubes on south roof 200l tank, just above the boiler in the back bedroom (boiler,in utility below)is where the hot water enters the bath room, fit isolation valve, on hot supply and hot supply from tank, so when i have enough hot in tank close the hot supply from boiler, and open hot supply from tank, will have a basin in same room where these isolators are,fed just from tank, so if it over heats can just open tap. that is the simple version, iknow i will have to wire stats to open valves, to stop over heat and stagnation. what i want to to know is,how ofton on a nice sunny day, would a 24 tube system, heat up a 200l tank?

 

[eaton]

24 tubes shouldn't stagnate on a 200l tank. You just need to buy a full kit from someone and get them to size it, sized properly stagnation doesn't happen.

 

[Gray0689]

24 tubes shouldn't stagnate on a 200l tank. You just need to buy a full kit from someone and get them to size it, sized properly stagnation doesn't happen.

Key words there sized properly don't guess

 

[eaton]

Yep that's the issue here, he needs to pick a make and then go with that spec. Although I feel like I'm banging my head against a wall on this

 

[Gray0689]

Yep that's the issue here, he needs to pick a make and then go with that spec. Although I feel like I'm banging my head against a wall on this

You never know mate

 

[gjcone44]

no your not lads, i am happy to take that advice, i want to keep it simple, 24 tubes is the max i can fit, the tank will fit in loft directly under the panel, but it will be a good 6-7 mtr run to pick up the bathroom hot water.