Advice on Thermal Store

[SimonH2]

There will never be any chance of the persons using this forum agreeing on a thermal store being the best solution.

That's a bit of an understatement

There is no perfect system - they all have problems and disadvantages. Including thermal stores.

Indeed.

Thermal store ticks most of the boxes. Completely passive - only moving part is the TMV on the DHW outlet. Main limitation being on the power capacity of the DHW coil which limits draw off rate.

Heat Bank (thermal store with external plate heat exchanger (PHE)) avoids the limited power output (PHE can be as large as you want to pay for), but introduce another pump.

Both can be open vented, or unvented. With uncontrolled heat source I believe unvented can be done but needs so much safety protection it's better to just go open vented. Open vented doesn't need someone with G3 ticket anyway.

The OP will get better advice somewhere like the Navitron forums which is populated by people not afraid of anything that isn't a combi, S-Plan or Y-plan

 

[JonasX]

Thermal store ticks most of the boxes. Completely passive - only moving part is the TMV on the DHW outlet. Main limitation being on the power capacity of the DHW coil which limits draw off rate.

Bang on Simon. A thermal store with a large DHW coil and also a CH take-off coil made of stainless steel will last and last and no sludge would ever enter the cylinder. They are super simple and as you say, few moving parts. No complex, expensive, safety pressure devices are needed.

Heat Banks can have their plate heat exchangers removed and descaled. You can also easily add a larger plate to improve DHW flow.

If the thermal store or heat bank is vented, there is no expensive G3 certified man needed to install and it does not need an annual service saving a lot of money per year.

The OP will get better advice somewhere like the Navitron forums which is populated by people not afraid of anything that isn't a combi, S-Plan or Y-plan

Warning! Do not mention rival products to what Navitron sell or you may get banned. The aim of the forum ultimately is to promote Navitron products. Guys on other forums have mentioned this.

 

[tomchapman]

Many thanks for all your replies.

Thermal store is definatly what I'm going with now, I just can't decide if I want an extra pump and plate heat exchanger, or go with an internal coil.

Seems a bit backwards that no power = no hot water for a shower when the hot water is at mains pressure. We don't have a lot of power cuts so its not the end of the world, and plate heat exchanger sounds more efficient and easy to change in the future when it scales up.

Do you think I should have the ASHP running through a "solar" coil in the store, or feed the store directly like the Aga?

Thanks.

Tom

 

[SimonH2]

Warning! Do not mention rival products to what Navitron sell or you may get banned. The aim of the forum ultimately is to promote Navitron products. Guys on other forums have mentioned this.

It's not quite that bad. Certainly being sponsored by Navitron they don't take kindly to promotion of other products, but you don't get banned for mentioning them in passing or as part of a wider discussion.

It's certainly a forum worth a visit by the OP.

 

[JonasX]

Many thanks for all your replies.

Thermal store is definatly what I'm going with now, I just can't decide if I want an extra pump and plate heat exchanger, or go with an internal coil.

Seems a bit backwards that no power = no hot water for a shower when the hot water is at mains pressure. We don't have a lot of power cuts so its not the end of the world, and plate heat exchanger sounds more efficient and easy to change in the future when it scales up.

Do you think I should have the ASHP running through a "solar" coil in the store, or feed the store directly like the Aga?

Thanks.

Tom, in a power cut a combi does not work either. Having three coils in a cylinder means the cylinder will be big. Having the plate will mean a smaller cylinder and the heat bank can operate at lower temperatures the bigger the plate - essential with an ASHP. The plates do deliver the DHW and have an oversized one and it will promote high boiler efficiencies as the water sent back to the bottom of the cylinder will be not much warmer than the mains temperature. If you have a condensing boiler (oil or gas), the cold water gets pumped to the boiler's return - the lower the return pipe temperature the higher the efficiencies on condensing boilers. Also the AGA will work a little harder, as will the Heat Pump.

If only having the AGA and Heat Pump heating the thermal store, also put in an electric immersion heater for full CH & DHW backup. And also have cylinder tappings for a boiler in case, in the future. Tappings maybe for a solar panel in the future maybe a good idea.