"Mike Holmes" wrote in message
ups.com...
I am shortly going to convert my conventional open vented DHW cylinder
into a Heat Bank following the design given at
http://wiki.diyfaq.org.uk/index.php?title=DIY_Heat_Bank

Best do it this way:

Read http://www.heatweb.com for an explanation of how heat banks work

1. Fit a Surrey type of flange in the top tapping of cylinder. 1" if you
can.

2. The plate heat exchanger connects to the Surrey flange port that is
immersed in the cylinder water. Drill a few holes in the protruding tube
that goes into the water to ensure heat is extracted from cylinders dome,
not being pumped to the bottom of the cylinder. The protruding tube has a
plate over the end to stop the water heat right to the bottom of the
cylinder.

3. The boiler flow is taken from the other connection of the Surrey flange
on the top of the cylinder. The return into the old cold feed tapping.

4. From the Surrey to the plate and then to the pump the to a spring loaded
check valve and back into the bottom cylinder port. Make a diffuser by
inserting 22mm pipe into the bottom cylinder port and drilling holes in and
stopping up the end with an internal pipe stop (available from BES). File
down the inside of a brass compression fitting that screws to the cylinder
port, removing the pipe stop so the pipe can go straight through. This will
spread the returning water mainly down, so it will not upset stratification
in the cylinder.

5. Two cylinder stats can be used to give a long efficient boiler recovery
burn. One stat about half way up and the other about 25% of the way up the
cylinder. Set bottom say to 70-80C, set top say to 60-65C. The stats must be
latched in with a relay.

6. The cold mains direct from the cold mains stoptap with no tee offs. Take
into the flow switch then into the bottom connection of the plate heat
exchanger and then to the DHW blending valve.

7. Have thermostatic shower mixers and take the hot supply for these
directly off the plate heat exchanger "before the TMV (blending valve). No
need to run DHW through two thermostatic mixers.

8. Install a phosphor de-scalar on the incoming mains pipe.

9. Install isolation valves on heavy usage appliances such as the washing
machine, and throttle back so it will not rob showers and baths of hot
water.

10. Have the F&E tank top up at the bottom of the cylinder and vent at the
top. You may want to vent from the boiler flow pipe.

11. Fill with inhibitor - about 1% of total system volume. An average system
is approx 100 litres, so a system has one 1 litre can. If say 150 litre
cylinder then two cans for the cylinder alone, which is three.

12. Fit a Magnaclean filter on the rads return pipe to the boiler.

The performance is brilliant and you will be delighted with the mains fed
showers and no vibrating power shower pump noise. High pressure mixers can
be on all appliances.

Gledhill will supply a Plate Heat X. The model for the 145 litre Systemate
will do. If you can get another cheaper source then try them. A 100kW plate
heat exchanger is needed

http://www.bes.co.uk or Screwfix will supply most of the fittings. They
don't do the plate heat exchangers.

Farnell will supply the flow switch http://www.farnell.co.uk Farnell number:
1006771 22mm compression joints.

Flow Switch, makers site: The FS06
http://www.gentechsensors.com/produc...asp?ProdId=113
This flow switch is about the best - very good.

If the boiler requires to be in a sealed system then have a cylinder with a
quick recovery coil an the boiler heats this ASAP. Most boilers can be
fitted to an open vented system.