Several years ago I received some (hopefully) good advice on this forum regarding changing and simplifying the plumbing surrounding my thermal store.
The store will transform from its convoluted plumbing which was following the manufacturer's (Gledhill) guidelines to a more simple/standard config in which 1. the boiler heats the store, 2. The solar heats the store, 3. The heating is pumped off from the store. (the much lauded 'neutral point')

The advice on this forum at the time was that I should install some check-valves to prevent the chance of thermosyphoning via the boiler and/or the heating, and my question regards this.

The boiler circuit will consist of; pipe from lower part of cylinder into 'cold' side of blending valve (to allow control of boiler return temp and hopefully force condensing whilst maximising output temperature to heat the thermal store from the top down). Output of blending valve into pump. Output of pump into boiler. Output of boiler into upper part of thermal store and also via T into 'hot' side of blending valve.
My question is; where do I put the check-valve? My thought is between output of boiler and cylinder, but are there any rules, such as always before a pump, or always after a pump etc, or does it really not matter?

Same question regarding the heating circuit; The heating will flow from the upper part of the cylinder into a pump, and then on to the rads, but should the check valve be before or after the pump?

Finally, I've already got check valves something like this; http://www.screwfix.com/p/22mm-single-check-valve/61237
are these going to be suitable for use in heating circuits as I just noticed that it says they contain plastic parts? (It would have to be pretty pathetic plastic to melt at less than 100 C !!) Also, are check-valves generally reliable?... would I be as well adding isolating valves either side to facilitate replacement, or am I being over cautious??

Thanks guys.

On Apr 17, 11:02*pm, pepper wrote:
Several years ago I received some (hopefully) good advice on this forum regarding changing and simplifying the plumbing surrounding my thermal store..
The store will transform from its convoluted plumbing which was following the manufacturer's (Gledhill) guidelines to a more simple/standard config in which 1. the boiler heats the store, 2. The solar heats the store, 3. The heating is pumped off from the store. (the much lauded 'neutral point')

The advice on this forum at the time was that I should install some check-valves to prevent the chance of thermosyphoning via the boiler and/or the heating, and my question regards this.

The boiler circuit will consist of; pipe from lower part of cylinder into 'cold' side of blending valve (to allow control of boiler return temp and hopefully force condensing whilst maximising output temperature to heat the thermal store from the top down). *Output of blending valve into pump. *Output of pump into boiler. *Output of boiler into upper part of thermal store and also via T into 'hot' side of blending valve.
My question is; where do I put the check-valve? My thought is between output of boiler and cylinder, but are there any rules, such as always before a pump, or always after a pump etc, or does it really not matter?

Same question regarding the heating circuit; *The heating will flow from the upper part of the cylinder into a pump, and then on to the rads, but should the check valve be before or after the pump?

Finally, I've already got check valves something like this;http://www.screwfix.com/p/22mm-single-check-valve/61237
are these going to be suitable for use in heating circuits as I just noticed that it says they contain plastic parts? *(It would have to be pretty pathetic plastic to melt at less than 100 C !!) *Also, are check-valves generally reliable?... would I be as well adding isolating valves either side to facilitate replacement, or am I being over cautious??

Thanks guys.

Active thermal storse for space heating are a waste of space if you do
the calculations.

Active thermal storse for space heating are a waste of space if you do the calculations.

Not exactly what I asked, but I must say I am still to be totally persauded of the benefits - mains pressure showers without pumps is great, but there are other ways to achieve that too.

On Apr 18, 8:04*am, pepper wrote:
Active thermal storse for space heating are a waste of space if you do the calculations.

Not exactly what I asked, but I must say I am still to be totally persauded of the benefits - mains pressure showers without pumps is great, but there are other ways to achieve that too.

You will find for space heating requirements, it is virtually
impossible to store sufficient heat to make significant difference.
Also the heat leaks away relatively quickly.

For domestic hot water, the costs/requirements are so low that it's
difficult to justify any large expenditure on elaborate systems..
Needs to be well insulated of course.
Which is why solar thermal systems have such a long payback period.

In my experience these complex systems rarely work, you would be
better spending the money on insulation and draught proofing.