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Pete C
 
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On Mon, 16 Aug 2004 22:05:30 +0100, "Harry Ziman" hziman at clara dot
co dot uk wrote:

We have an old farmhouse with the hot water/heating system confidgured as
follows.


Boiler 1: 110,000 BTU 16 radiators in the "front" of the house

Boiler 2: 110,000 BTU 6 radiators, hot water in the "back" of the house

Aga: Hot water in the front of the house

In case you are wondering the house was once divided into two each with its
own heating and hot water system - they are independent with their own
header tank, timer, pump, hot water tank.

Needless to say this is not very convenient - to heat one of the bedrooms we
need to put the second boiler on. The two boilers sit next to each other in
the boiler room so we would like to combine the systems. The question I
would like to ask is how to organise the boilers. Do they go in series (i.e.
water through one then the other) or parallel (i.e. split the water flow so
it can run through either boiler and then recombine). CanI safely run one
boiler and when I need the extra heat switch the second one on? One person
has todl us that the boilers must go in series and both be controlled
identically - same temperature and same time-controls.

Before anyone asks, I know that the header tanks need sorting out so there
is only one. Also, I do not want to go to the expense of a new boiler with
the capacity for the whole house.

We would also like to rationalise the hot water system so the Aga heats
water for the whole house. This is a little more involved. Can I direct the
flow through two separate hot water tanks? If not, how about a valve and a
timer to regularly switch alternate from one to another. Failing that I
guess I will need to remove one of the tanks and accept that it will take a
long time for hot water to flow to some parts of the house.

Do let me know if any of this fails to make sense and I will try to explain
further.

Thanks

Harry


Hi,

I'd put both boilers in parallel, with a decent size pump feeding
both.

Then put a 'pipe stat' on the return to switch off one of the boilers
when the system is up to temperature and the heating demand is low.

If both boilers were in series you might get 'kettling' in the second
boiler when both are on, or the second might cut out when the first
cuts in.

cheers,
Pete.