Thermal Store Installation

[electrogear]

The only sane use of a thermal store would be to link up a gas or oil boiler to an uncontrolled heat source....Only other time one would be fitted is when a customer with more teeth than brain cells is allowed to use Google

Actually, it was a self appointed "expert" on here that put me onto thermal stores. I asked my plumbers opinion and he also recommended a thermal store, so perhaps the braindead are a bit closer to home than you think

After conversations with a number of other plumbers and friends with both systems it does now seem fairly conclusive (to me) that unvented is the way to go. Thanks for everyone's input.

 

[Dan Robinson]

No worries.

For reference I would look at 210 or 250 litres for gas only. 250 - 300 if using solar thermal.

 

[shambolic]

Yep but remember a 400litre cylinder supplying a 20litre a minute large head rainwater shower will only give you 20 minutes of shower.
I have both in my house. The combi does my main ensuite shower but the cylinder does my bath and anothe few outlets.

 

[Dan Robinson]

Yeah - but you've built yourself a castle.

Do you have to notify the water authorities when you run the bath?

 

[shambolic]

Yeah - but you've built yourself a castle.

Do you have to notify the water authorities when you run the bath?

No but then I do have a river in the garden and a separate Spring fed supply to the house from the reservoir behind us.
Pe still not finished 11 new Windows fitted to the newer building(renovated 40yr ago) to match the new bit and the 300 yr old bit that we renovated.
Still 7 windows to go, a dining room, bedroom and ensuite and dressing room then the outside.
Getting there now. Sitting in the lounge just letting the 11kw wood burning stove die down before bed.
50acres of woodland helps with free fuel

 

[Dan Robinson]

Nice.... all those PCB's eh?

 

[shambolic]

Nice.... all those PCB's eh?

Yep the auld ones burn well in the fire as long as you don't breathe in the fumes.

 

[Madrab]

Actually, it was a self appointed "expert" on here that put me onto thermal stores.

Just to point out, I don't think any 'self appointed "expert" as it was put, was directing anyone towards a thermal store as the preferred option. I believe you were given the choice and their pros and cons that fitted your criteria. Either a thermal store or un-vented could deliver the solution to your hot water pressure issue.
I believe the thermal store was then adopted as the preferred option due to it not requiring the need for the cost of a qualified engineer to fit and service as it could be self serviced?

As always the best solution for a given situation would all come down to a proper design exercise, as was also mentioned.

 

[Biggles..]

Yep but remember a 400litre cylinder supplying a 20litre a minute large head rainwater shower will only give you 20 minutes of shower.
I have both in my house. The combi does my main ensuite shower but the cylinder does my bath and anothe few outlets.

I know your a hard Scott, but surely even you can't shower in water at or above 60degC.

400litres/20lpm about 32mins at a more southern temp of 45degC.

 

[bernardgreen]

Actually, it was a self appointed "expert" on here that put me onto thermal stores. I asked my plumbers opinion and he also recommended a thermal store, so perhaps the braindead are a bit closer to home than you think

I also know plumbers who would reccomend thermal stores in some situations.

After conversations with a number of other plumbers and friends with both systems it does now seem fairly conclusive (to me) that unvented is the way to go. Thanks for everyone's input.

These same plumbers are in two minds about vented or un-vented. Odd that more of them have vented systems in their houses than those who have un-vented systems.

My hot water tank in the bath room is vented and supplies the bath and wash basins with hot water, it also act as a thermal store to heat mains water passing through a second coil to supply the shower. A thermal store with no sludge build up and mains pressure shower. With none of the maintenance costs / problems of a pressurised system.

 

[Corgigrouch]

I also know plumbers who would reccomend thermal stores in some situations

Which situations would they recommend a thermal store then?

 

[bernardgreen]

Which situations would they recommend a thermal store then?

When the supply of heat is near continuous but at a maximum rate that is less then the rate required for a few hours a day to warm the house.

Or to provide a large "pulse" of heating to take a cold house to a comfortably warm house in a few minutes without having to size the boiler to supply that short duration high output.

An example is a thermal store used to store heat from a water sourced heat pump mechanically powered from a small water wheel.

 

[Corgigrouch]

Which situations would they recommend a thermal store then?

When the supply of heat is near continuous but at a maximum rate that is less then the rate required for a few hours a day to warm the house.

Or to provide a large "pulse" of heating to take a cold house to a comfortably warm house in a few minutes without having to size the boiler to supply that short duration high output.

An example is a thermal store used to store heat from a water sourced heat pump mechanically powered from a small water wheel.

So not applicable in any way shape or form in the OPs situation

 

[JohnHarrison]

Electrogear, go the way you think is best because it is the best in your circumstances. You are obviously a professional by your attitude. You want solar later, so the thermal store is the best option. Unvented cylinder store high pressure water in a house and need G3 to fit and G3 to service, which costs. You still have the explosion potential. Have the radiators off the thermal store as well via a coil. The ignorance on thermal stores by "professionals" on this forum is apparent. Quite unbelievable. If you have a thermal store with the water in the cylinder not running through the rads sludge does not occur. Sludge only happens when the ferrous from the rads dump the magnetite into the store. Standing losses on unvented cylinders and thermal stores are about the same.

The best way is to have a thermals store cylinder with the following:

1. Vented with maybe a header tank just over the cylinder - can be remote in loft.
2. Heated directly via the boiler.
3. Radiators taken off the store via coil - the rad water is separate to the stored water, hence no sludge.
4. A second solar coil.

The stored water will circulate only through the boiler. The only ferrous is the pump, This can be a brass pump and then eliminate all ferrous in boiler and store. The so-called "professionals " think all stores create sludge. Just the odd 1 litre of X-100 needs to be poured into the store every 3 to 4 years just to be sure.

The rad circuit can have a sealed system kit fitted with its own pressure vessel to prevent air ingress. Have the rad circuit fed by a Smart pump. Then TRVs on all rads. If another zone is needed then add a pump with check valve on each circuit.

The solar coil can be connected later.

The boiler can be very big giving a super quick recovery. For e.g., if you get a cheap deal on 50kW go for it, as long as the flow and return pipe sizes are OK. Your gas meter is capable of 62 kW. The bigger the boiler the smaller the store and the lower the standing losses. A thermal store cares not a jot what size the boiler is. Put a large boiler on a small rad circuit and you have boiler trouble. The same with a small coil in an unvented or vented cylinder. The thermal store is a fantastic buffer as all aspects operate independently. The boiler will always be running at its most efficient with full flow through its heat exchanger. It heats up the cylinder in one long efficient burn. Boilers really do last when only heating thermal stores being in the ideal hydronic environment. They rarely cycle and two simple anti-cycle thermostats can be fitted if you want to stop it 100% - I advise to do.

You can also fit a high kW immersion as a backup, for CH & DHW.

Beware of so called "professionals" who say a Vaillant and unvented cylinder is the only way to go. No doubt these "professionals", who specialise in drains, will come back with ad hominem attacks, with technical substance and experience lacking. Wait and see. It is hilarious to read. Guaranteed to happen.

 

[JohnHarrison]

Electrogear, as an alternative, you could fit a:

1. Worcester Bosch Greenspring instant water heater delivering 21 litres/min. It is 50kW. Cost about £1,300
2. Fit a small, cheap, system boiler doing the CH.
3. A vented solar cylinder with a big mains pressure coil with mains cold water being preheated and feeding the Greensping. Could be fitted later.

You are then diving and ruling with each system being simple. Also if the gas meter is being exceeded, have a flow switch on the cold feed to the solar cylinder/Greenspring which switches out the system boiler (via the boilers's stat circuit) when DHW is drawn off. Then you have a simple priority system and the 6 cu Metres/hr (62kW) gas meter limit is not exceeded. The diversity factor calc may put you within the meter's limit.

Worth pricing up. It may save space as well.