"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...
HI

Doctor Drivel wrote:

"Adrian" wrote in message
...

Questions:
You have a thermal store/heat bank heated via a heat pump. It serves
CH and DHW via a plate heat exchanger. Is that so?

Not quite.

The heat store is simply a large tank containing water that's
circulated through the radiators / dhw tank. The circulating water is
heated by a heat pump (ground source)


Is it a pressurised thermal store? Or is it open vented - uses an
F&E tank to top it up?

No - not pressurised - it's part of the open f&e-tank-fed heating
circuit.

Adrian, where is the thermal store vented from, on the store and where
is the cold feed connected to it?



The easiest way for me to describe it is....

Imagine a conventional, non-pressurised, boiler system.
Replace the boiler with the Heatpump.
On the return circuit from the radiators / hot-water tank to the
'boiler' (and immediate 'before' the boiler), insert a big water tank -
with the return from the heating circuit piped to the top of the tank
and the return to the boiler piped from the bottom of the tank.

No separate vents or feeds connected to the store.

Heatpump and store are at ground-level, f&e tank is in the loft...

Hope that makes it clearer?

As clear as mud. Firstly, is this right? "the return from the heating
circuit piped to the top of the tank and the return to the boiler piped
from the bottom of the tank".

Absolutely right.


The return from the DHW cylinder and CH to the "top" of the thermal
store? Is that right?

Same as above...


Where is the CH flow connected to the system?

Flow goes from the heatpump, through the rads or dhw cylinder coil, then
back as the return.....


Where is the heat pump's flow connected to the system?

See above


The vent pipe from the F&E tank. Where is it connected to the system?

Top end of the dhw cylinder coil...

The cold feed pipe from the F&E tank. Where is it connected to the
system?

Same place as the vent pipe.


Look - I'm clearly not explaining this well - I'll see if I can find time
to sketch the system tomorrow or early next week.

The original question was 'is there something that I don't know about
using automatic air vents on circulating water systems?' - - and it seems
that I maybe need to create a point on the return circuit that is
deliberately higher than the store - but very close to the store, and fit
the air vent there....

You have a "buffer" only on the return pipe to the heat pump to ensure cool
water is fed back to the heat pump. This give the large delta T needed for
heat pump operation. This is not a thermal store.

A large tall heat bank/thermal store using a plate heat exchanger for DHW
probaly would have been better and using off-peak electricty could be heat
up during the night.

If the auto air vent is not working it is duff.