Hi chaps,
quick query here, We've been having hot water too hot for a little
while now, and my conclusion was that my three port valve or the
actuator was not working correctly so every time the heating was on, the
hot water was on too.

Anyhow, I took the carpet up today to have a look, and the motorised
actuator does change position when hot water only is on (no heating)
and changes back when I put the heating on and the hot water off.

I've freed off the spindle to the valve which was a bit sticky. But it
moves with finger pressure now.

However, when I started initially, after everything had been off for
several hours, the motorised actuator was still quite warm, about 40C

Is this right or does it indicate a problem with the motor trying to
turn all the time and getting hot?

It's a Danfoss motorised valve fitted in 1998.

Can I just replace it with a similar item if it is faulty?

Thanks for your advice.

dedics


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Ian & Hilda Dedic wrote:
Hi chaps,
quick query here, We've been having hot water too hot for a little
while now, and my conclusion was that my three port valve or the
actuator was not working correctly so every time the heating was on, the
hot water was on too.

They do run warm.
It would be a good idea to relocate the valve so that it's at 90
degrees, so that the pipe doesn't additionally heat it.
I suspect putting the valves in the return, if they can.

In an earlier contribution to this discussion,
Ian & Hilda Dedic wrote:

Hi chaps,
quick query here, We've been having hot water too hot for a little
while now, and my conclusion was that my three port valve or the
actuator was not working correctly so every time the heating was on,
the hot water was on too.

Anyhow, I took the carpet up today to have a look, and the motorised
actuator does change position when hot water only is on (no heating)
and changes back when I put the heating on and the hot water off.

I've freed off the spindle to the valve which was a bit sticky. But
it moves with finger pressure now.

However, when I started initially, after everything had been off for
several hours, the motorised actuator was still quite warm, about 40C

Is this right or does it indicate a problem with the motor trying to
turn all the time and getting hot?

It's a Danfoss motorised valve fitted in 1998.

Can I just replace it with a similar item if it is faulty?

Thanks for your advice.

dedics

3-port valve actuators sometimes appear not to obey the laws of physics -
even though they do, in reality.

In particular, they can remain powered and in the mid or CH position when
nothing particular is happening. It requires a demand for HW-only to bring
it back to the HW position. [This actually works to your advantage. Imagine
a situation where the HW demand is satisfied and the CH is cycling on and
off on the room thermostat. If the valve returned to the HW (unpowered)
position every time the room stat switched off, there would be delay every
time the stat switched back on, while the valve moved back to the CH
position, before the boiler and pump would start].

Check what position the valve is in when the actuator is warm even though
everything is off. If it's anywhere other than in the HW position, the
manual lever will flop about freely.

If you want to force the valve back to the HW position, turn off the whole
heating system at the FCU (not the programmer). You should then see/hear the
spring return operate. If it does that, it's probably ok.
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In article ,
"Roger Mills \(aka Set Square\)" writes:

If you want to force the valve back to the HW position, turn off the whole
heating system at the FCU (not the programmer). You should then see/hear the
spring return operate. If it does that, it's probably ok.

It can still stay in the middle position when all power is
removed. This is because the middle position is held by locking
the rotor with DC current, and it ends up magetising the yolk,
often enough to prevent the spring return. In order to guarantee
spring return to the HW position, a tiny AC current is supplied
via a resistor to degauss the yolk, which hence needs power.

--
Andrew Gabriel

In an earlier contribution to this discussion,
Ian & Hilda Dedic wrote:


I've freed off the spindle to the valve which was a bit sticky. But
it moves with finger pressure now.

That may have been the problem. If the valve was too stiff to move, the
actuator may not have been able to move it all the way to the CH-only
position - in which case the HW would have been (over)heated at the same
time.

Run it for a bit, now you've freed it, and see what happens.

[See my other post concerning the actuator being warm]
--
Cheers,
Roger
______
Please reply to newsgroup.
Reply address IS valid, but is disposable in the event of excessive
spam.

Roger Mills (aka Set Square) wrote:
In an earlier contribution to this discussion,
Ian & Hilda Dedic wrote:

I've freed off the spindle to the valve which was a bit sticky. But
it moves with finger pressure now.

That may have been the problem. If the valve was too stiff to move, the
actuator may not have been able to move it all the way to the CH-only
position - in which case the HW would have been (over)heated at the same
time.

Run it for a bit, now you've freed it, and see what happens.

[See my other post concerning the actuator being warm]


Thanks for that, It sounds like everything is ok, I'll run the system as
normal and try your other tests if I get scalding water again.

cheers
dedics


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