At the moment I have pumped CH and what was gravity DHW but when the replacement boiler (Ideal Mexico Super 2) was fitted it made the DHW inefficient due to the distance from the tank and the run vertually level across the length of the kitchen wall for about four meters before going up to the tank in the bathroom above, so the plumber fitted a pump next to the tank to help. It's been like this now for about six years.

Whilst doing another job I found that the heating pipes leave the boiler in 22mm to the first radiator upstairs then all the rest are in 15mm so in the spring I plan on changing this to 22mm to all the radiators with 15mm tails.
Whilst doing this I thought about changing the system to a proper fully pumped system using two motorized valves and one pump.

What I was thinking of doing was keep the 28mm from the boiler and run this to a pump then split to two motorized valves then carry on with the original 28mm to tank because it will be a major job to remover the 28mm and replace it with 22mm and from the other valve drop down to 22mm to join up with the original CH piping. The fill and expansion I will move so they go direct to the boiler on the old CH tapings as it shows on the boiler manual.

Could anybody tell me if this is doable, or a better solution?

On 23/01/2013 14:56, Trevor Smith wrote:
At the moment I have pumped CH and what was gravity DHW but when the
replacement boiler (Ideal Mexico Super 2) was fitted it made the DHW
inefficient due to the distance from the tank and the run vertually
level across the length of the kitchen wall for about four meters
before going up to the tank in the bathroom above, so the plumber
fitted a pump next to the tank to help. It's been like this now for
about six years.

Whilst doing another job I found that the heating pipes leave the
boiler in 22mm to the first radiator upstairs then all the rest are
in 15mm so in the spring I plan on changing this to 22mm to all the
radiators with 15mm tails. Whilst doing this I thought about changing
the system to a proper fully pumped system using two motorized valves
and one pump.

More 22mm may help - then again, are you having difficulties with the
current setup not keeping the rads hot enough?

What I was thinking of doing was keep the 28mm from the boiler and
run this to a pump then split to two motorized valves then carry on
with the original 28mm to tank because it will be a major job to
remover the 28mm and replace it with 22mm and from the other valve

No real advantage in changing for a smaller pipe in this case...

drop down to 22mm to join up with the original CH piping. The fill
and expansion I will move so they go direct to the boiler on the old
CH tapings as it shows on the boiler manual.

Could anybody tell me if this is doable, or a better solution?

Its doable - the boiler won't have any problem running fully pumped.
There are 4 tappings on the heat exchanger, you normally plug two of
them for when using fully pumped arrangements.

The pair of two port valves is fine, although it makes it harder it
integrate pump overrun, which is well worth doing on a cast iron lump of
a boiler like that.



--
Cheers,

John.

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