"Chris McBrien" wrote in message
. ..
First, regarding the dual venting of both tanks.
In all fairness I did this system 22 years ago and first time I only
properly vented the one tank. I ASS-U-ME'd that the two
connecting/transfer
pipes would allow the air back into the unvented tank... WRONG ! The
first
time I drained the system (during the installation) I popped my head into
the loft and 14.7 psi on the outside and 0psi on the inside of the tank
had
done its job and crushed the tank. We/I learned from that and put a hole
through 23 inches of Granite to get a vent pipe through and back to the
cold
water source tank. Problem solved.
The motorized zone valve, switched with the pump, seems to be the logigal
answer. Beleive it or not I did buy one some seven years ago but.....
If I put the immersion into the upper FIRE tank I would not have any hot
water in the lower IMMERSION tank unless I used the transfer pump. The
idea
was to get a second load of hot water into the IMMERSION tank from the
FIRE
tank quickly, rather than switch the immersion on again.
The whole problem is caused by this 23 inch Granite wall that virtually
splits the house and the distance between the two tanks. I have to have
the
FIRE tank right above the fire so that the pipe run to the indirect
heating
loop is fairly short.
Thanks for the "Swing Valve" pointer, never knew they existed. Why only
BSP
fitting? Are they more of an industrial device.
Thanks again guys. This is a great board.
Firstly terminology:
tank = cold water storage tank
cylinder = hot water storage cylinder
Do don't mention where the hot water draw-off comes from and how the two
cylinders are vented.
I would do this:
1. Have the FIRE cylinder as a "pre-heat" for the IMMERSION cylinder
2. No pump between.
3. Take the cold feed of the cold water storage tank into the bottom of the
FIRE cylinder.
4. From the top of the FIRE cylinder, DHW draw-off, take an open vent over
the cold tank
5. Take a pipe from the top of the FIRE cylinder, DHW draw-off connection,
to the cold feed of the IMMERSION cylinder.
6. From the top of the IMMERSION cylinder have a vent pipe over the cold
water storage tank, and from pipe take the hot draw off to the taps. So,
eaxch cylinder has a vent pipe each.
7. Remove the two cyldiners connection pipes.
8. Remove the pump.
- Both cylinders will be vented, so no implosions.
- No natural circulation between the cylinders
- One cylinder feeds the other. This acts as preheat in winter and pre-heat
in summer too as the water in the FIRE cylinder will be warmer than the
water in the cold water storage tank
Simple no need for pumps.
|