Thermal Stores and all that

[9fingers]

Next years paper round-2-it design project for me is going to be installing a thermal store/heatbank with a solar collector on the roof and mains pressure hot water for the house.

I would very much like to be able to swap notes and generally get experience from anyone who has gone down this path already.
Of particular interest are the makers/suppliers of components for DIY installs and the choice of control systems.
Most of my web searches seem to lead to Gledhill products as a market leader but they don't seem to offer systems with plate heat exchangers which I read are preferred in hard water areas like mine.

Anyone been this way before?

TIA

Bob

 

[flying haggis]

We have had a Gledhill mains presure hot water system since we built the house and I can thoroughly recommend them. We also from day one fitted a water softener as we have hard water as well. If I recall gledhill systems dont care how the heat store is heated. I cant see any special controls being needed because if the solar collector has raised the temp of the heat store sufficiently then the normal in-tank thermostat will not call for heat from a boiler. Although what the system would do if the solar heating was to be greater than the requirement of the heat store I dont know.

 

[Steve Maskery]

Bob, drop Eric the Viking a nudge. He's done a lot of work on this.
S

 

[9fingers]

Thanks Steve.

Flying Haggis, Can you tell me which Gledhill system you have please. They seem to have many, each with differing control systems.
I guess the water softener is one approach but not one I want to go down having experience a "softened" household in the past.
If possible I would like to use a plate heat exchanger which is easy to de-scale if needed.

Thanks
Bob

 

[flying haggis]

Hi Bob
When you say you require a plate heat exchanger do you mean the one that is in the tank, because surely to descale it you would have to take it out of the tank. Gledhill do recommend a scale inhibitor if hardness exceeds 200ppm. FYI I have a boilermate II and if only for the mains pressure hot water available in the shower I like them. Does take some getting used to having your cylinder "plumbed backwards" as my plumber put it when he had to figure out how to fit it!

 

[sparkymarky]

bob, if you only want to connect a solar system and boiler then this is what you need - http://www.google.co.uk/products/catalo ... ps-sellers.

you mention that you have hard water, if you get a large amount limescale stay well away from plate heat exchangers as the limescale will clog the channels reducing the efficiency of the system. also if you have a power cut you will have no hot water.

alternatively how much room do you have? have you considered a `store` open vented cylinder (like this http://www.screwfix.com/p/rm-direct-cop ... 50mm/49608) next to a mains pressure storage cylinder (like this http://www.screwfix.com/p/rm-stelflow-u ... 0ltr/42783) you could then link the flow / return from the store to the cylinder using a circulating pump and single channel zone valve. with a separate store you could add as many heat sources as you like (as you can cut in a flange to this type cylinder) controlling the max temp of the store with a heat leak into a rad / towel rail controlled by a cylinder thermostat set at 85-0c all the separate heat sources could be controlled by pipe thermostats.

hope this helps, if you have any questions let me know.
mark.

 

[9fingers]

Hi Bob
When you say you require a plate heat exchanger do you mean the one that is in the tank, because surely to descale it you would have to take it out of the tank. Gledhill do recommend a scale inhibitor if hardness exceeds 200ppm. FYI I have a boilermate II and if only for the mains pressure hot water available in the shower I like them. Does take some getting used to having your cylinder "plumbed backwards" as my plumber put it when he had to figure out how to fit it!

Hi Flying Haggis,

A PHE is deliberately outside the cylinder. A major advantage is then that it can be taken out for descaling. This appears to be the problem with gledhill as they only seem to offer internal coil heat exchangers. These can be descaled but it is more of a performance to do.
I'll have to weigh up the pros & cons of the coil system

Cheers

Bob

 

[9fingers]

bob, if you only want to connect a solar system and boiler then this is what you need - http://www.google.co.uk/products/catalo ... ps-sellers.

you mention that you have hard water, if you get a large amount limescale stay well away from plate heat exchangers as the limescale will clog the channels reducing the efficiency of the system. also if you have a power cut you will have no hot water.

alternatively how much room do you have? have you considered a `store` open vented cylinder (like this http://www.screwfix.com/p/rm-direct-cop ... 50mm/49608) next to a mains pressure storage cylinder (like this http://www.screwfix.com/p/rm-stelflow-u ... 0ltr/42783) you could then link the flow / return from the store to the cylinder using a circulating pump and single channel zone valve. with a separate store you could add as many heat sources as you like (as you can cut in a flange to this type cylinder) controlling the max temp of the store with a heat leak into a rad / towel rail controlled by a cylinder thermostat set at 85-0c all the separate heat sources could be controlled by pipe thermostats.

hope this helps, if you have any questions let me know.
mark.

Hi Mark,
Great to get a reply from a professional!

I have a strong preference for a vented thermal store as it removes all the grief/hassle with inspections on pressurised DHW systems.
Ideally I'd like to stick with a single cylinder as the space is a little restricted.
My thinking behind use of a PHE system was that I could easily remove the HE to descale it, compared to a coil which would have to be done in-situ. I have however come up with a scheme to descale a coil so that might be less of an issue.
I guess as the main manufacturer (Gledhill) does not seem to supply PHE systems it must indicate a market preference for coils.
My primary heat source will be a gas system boiler so I don't expect to have too many issues with excess heat. However dumping excess heat from peak solar input via a towel rail is food for thought.

Cheers

Bob

 

[houtslager]

The route I am intending is this - 2 rayburns with wet backs, 1 large solar collector going into a large horizontal thermal store.as linked here =

http://www.nobel.gr/en/apollon/index.php

problem at the moment is getting a qoute for s&h

hth,

k

ps nobel have I believe a UK division

 

[Deejay]

Morning Bob

I looked into this a few years ago. In the end, I didn't do it, but found Grant UK a good source of information.

They do a good range of cylinders, both vented and pressurised.

There's all sorts of stuff on their website at

http://www.grantuk.com/

Cheers

Dave

 

[9fingers]

Morning Bob

I looked into this a few years ago. In the end, I didn't do it, but found Grant UK a good source of information.

They do a good range of cylinders, both vented and pressurised.

There's all sorts of stuff on their website at

http://www.grantuk.com/

Cheers

Dave

Thanks Dave, lots of interesting stuff on the Grant website! I'd not come across them before

Bob

 

[Dibs-h]

Bob

I'd be inclined to use a PHE as they are more performant than a coil in the tank. You might find the following useful,

http://www.heatweb.com/products/cylinde ... atbank.htm

HIH

Dibs.

p.s. A solar collector (evacuated tubes and heat store is also on my "round to it" list at some point.

 

[RogerS]

Have you thought about geothermal, Bob?

 

[9fingers]

Yes I have Roger and dismissed it on cost/access grounds a few years back.
I don't think it will have got any cheaper to drill but I suppose their might be some more compact drills around now.

Have you done this?

Bob

 

[RogerS]

Yes I have Roger and dismissed it on cost/access grounds a few years back.
I don't think it will have got any cheaper to drill but I suppose their might be some more compact drills around now.

Have you done this?

Bob

No I haven't but our neighbour has..uses a vertical borehole....he has done a huge amount of research and a spreadsheet on virtually all forms of alternative energy. An ex-astrophycisist from Qinetic. I've emailed you a photo of his first water strike! I am sure that he'd be happy to exchange information about it.

 

[dickm]

When you say "geothermal", do you mean actual geothermal (drilling down a km or so to hot rock) or just a ground source heat pump? If the latter.......... OK, don't get me going about the idiocy of heat pumps :twisted:

Interesting that there has suddenly been an upsurge in interest in true geothermal up here; sitting on granite and surrounded by companies that are used to drilling miles below the surface makes it seem a pretty obvious option.

 

[Digit]

Long over due Dick, a totally safe, environmentally friendly, green energy source that is pretty well limitless, so what do we get?
Windmills!

Roy.

 

[dickm]

There was a major geothermal project in Cornwall back in the 70s/80s. Not sure what happened (I suspect the oil companies warned the Govt off supporting it), but it quietly died. With the SNP's interest in renewables they will probably support geothermal up here, at least publically.
3 big turbines near us here when we moved in 2007, 23 now and counting - but I like them

 

[Digit]

I first became aware of the effectiveness of geo thermal some years ago Dick. Southampton? university were pushing the idea, and I have never forgotton the retort by the Wilson government that the idea lacked authority as the anticipated life of a borehole was only 30 yrs.
As a friend commented, 'and the life of a reactor is....?'

Roy.

 

[Jamesc]

I first became aware of the effectiveness of geo thermal some years ago Dick. Southampton? university were pushing the idea, and I have never forgotton the retort by the Wilson government that the idea lacked authority as the anticipated life of a borehole was only 30 yrs.
As a friend commented, 'and the life of a reactor is....?'

Roy.

This is up and running today see http://www.southampton.gov.uk/s-environment/energy/Geothermal/ I know very little about it other than I walk past it when I am dragged (kicking and screaming) into the shops in Southampton.

James