Re: Re: [OT] ishh central heating controls

[NEIL BALL <neilball@xxxxxxxxxxxxxxx>]

Could it not have been a hot water priority system? I've come across many
houses that use this approach as the boiler is effectively undersized and
cannot supply enough heat for the heating and hot water at the same time.
The priority system allows the boiler flow temp to stay high avoiding
poitentially damaging condensation forming inside the boiler and allowing
the hot water to be heated as quickly as possible. This is at the expense
of the heating circuit which obviuously gets no heat from the boiler while
the hot water calls for heat.

Regarding minimum flow rates through the boiler and pump run on, a proper
automatic bypass would be a better option IMHO as this will guarantee the
minimum flow rate for the boiler is maintained under all conditions and
that the pump always has somewhere to move it's water.

Neil B.

Gary Jenkins <gjenkins@xxxxxxx> wrote:


3) the valves. Personally i dislike 3 way valves ever since i spent
ages trying to work out why my cousins central heating turned off
for an hour or so when someone had a bath. the valve was both plumed
and wired incorrectly causing the system to shut off the heating
until the water tank was hot again! any way- id say you are best to
swtich to two way valves, expecially if from a Home automation point
of view- it give the maximum control. You can also use a two way
valve to shut off large areas of the house - for example i will
eventually put one in to stop heating the lounge in the mornings on
weekdays when its not used.

Word of warning though, most CH/HW systems are different- if you do
replace your 3 way for 2 two ways you'll need to review the
appropriateness of the wiring configuration. Some systems will use
a "pump run on" system to keep the water flowing round for a few
minutes once everything is shut off so the water in the heart of the
system cools down a little- and if this is the case you need a
length of pipe bettween the pump output and the return pipe with a
gated stop  cock in it. Otherwise the pump will pump against two
closed valves and the water will have no where to go- damaging the
pump.



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