Anyone know of any issues with Honeywell 3 port mid position valves, i.e.
installation, location or in service problems etc., I've had three or four
go faulty in the last 4 years since the system (and I hasten to add) was
professionally installed and it sounds like I might be approaching another !
It's either been problems with the valve it's self or the motor drive not
operating (opening the required port(s)) and thus causing the boiler to
overheat and cut out due to there being no flow - and causing hot water and
steam to be forced up into the boiler feed / expansion tank :~(
I've never come across a problem with them, at least not the way you
say, they'll normally go on for years. It sounds as if it's not been
installed correctly. Check the honywell site for your valve and have a
look at the technical specs and data sheet.
Should be very reliable though motor life varies dramatically with
temperature. Do you have unusually high ambient/flow temperatures or high
spec supply voltage?
Otherwise I have seen the rubber 'ball' which directs the flow to have
swollen for some reason, something in the system water assumedly. As you
describe a complete blocking of the flow which normally could not happen
with a three port valve, this could be the case. Perhaps you could do a
complete drain and flush next time, or maybe Honeywell would be interested
in examining your valve.
Not sure what you mean by that, but if you mean making steam, hammer blow
type sounds, and forcing water up into the feed / expansion tank, YES :~(
One pipe form the boiler is VERY hot (can't touch it for more than a second
or two) and the other is not more than warm. This morning there was not heat
in any radiator and the HW hasn't been re heated....
I think it would be recommended to fit a frost protection kit to the
components in the loft. Assuming the boiler is in the loft also you
want a wall mounted frost stat by the boiler and a pipe stat on the
return, connected in series across the permanent live feed and the
trigger wire on the valve, usually the brown.
this last part dosnt make sense as the valve will never shut both ports no
flow will be caused by a pump failure
if the valve is not powered the hw port is open if it is the ch port will
open or a blockage in the system
I agree entirely. Unlike using two 2-port valves - which can both be closed
at the same time - the 3-port valve doesn't have a position which shuts off
all the flow, and is unlikely to be the cause of your current problems. The
water always has somewhere to go unless all your radiators have TRVs on them
and they are all shut. If this *is* the case, you need to make some design
changes to the system!
It is far more likely that your lack of flow is due to problems with the
pump. How is this wired - is it simply wired in parallel with the boiler or
is it connected to the boiler's pump-over-run connection?
Yes the pump is connected via a pump-over-run connection. It's looking like
a defective sensor on the boiler, there is no electrical feed to pump.
I starting to suspect this / might / have been the (intermittent) fault
since the boiler was first installed and not the three position valve.......
Thanks to all for the replies.
You *have* got a permanent live feed to the boiler in addition to the
switched live, haven't you? Without this, the pump won't over-run - but it
will still run when the switched live (coming from the programmer and/or
room stat) is on.
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