Is this article a Red Haddock ???

[JohnW2]

Over the years, the most troublesome part of our heating system, has been the 3-port valve actuator. A basically simple device, but under tremendous strain, from a spring, wound up by a constantly powered, stalled clock type motor, to retain the valve open. Such a daft idea, I had it in mind to design something better, and more reliable, to operate the valve.

Indeed. It's always seemed totally daft to me - to the extent that I initially told people that they surely couldn't be right in saying that that is how they work. To have a motor which spends the vast majority of its life 'stalled' seems just plain crazy - and, as you say, it surely would be possible to design something more sensible?

 

[ericmark]

Seem to remember there was a sequence of events which could leave it activated even with heating off?

 

[ebee]

"a spring, wound up by a constantly powered, stalled clock type motor, to retain the valve open. Such a daft idea,"

I must admit that when I first came across it I thought the same and in the heating fraternity it is thought of as normal.
It mightjust be that it keeps the cost down and therefore not too relevant.
Someone might know the answer, I do not.

 

[Harry Bloomfield]

I must admit that when I first came across it I thought the same and in the heating fraternity it is thought of as normal.
It mightjust be that it keeps the cost down and therefore not too relevant.

I, numerous times, cursed the whole idea.

 

[JohnW2]

I must admit that when I first came across it I thought the same and in the heating fraternity it is thought of as normal.

Indeed - as I recently wrote:

Indeed. It's always seemed totally daft to me - to the extent that I initially told people that they surely couldn't be right in saying that that is how they work. To have a motor which spends the vast majority of its life 'stalled' seems just plain crazy ...

It mightjust be that it keeps the cost down and therefore not too relevant.

Maybe, at least the initial cost. However, I'm not so sure about the long-term 'cost over time', since I can't help but think that a motor which spends so much of its life 'powered but stalled' is probably going to need to replaced appreciably more often/frequently than one which is used more sensibly?

Someone might know the answer, I do not.

Same here!

 

[Harry Bloomfield]

which spends so much of its life 'powered but stalled'

They are simply stalled, by the insertion of a diode, once the desired position is obtained.

 

[JohnW2]

They are simply stalled, by the insertion of a diode, once the desired position is obtained.

Can you perhaps help me to understand that statement?

 

[Harry Bloomfield]

Can you perhaps help me to understand that statement?

When the actuator, is in the correct position, to trigger the microswitches, a diode appears in series with the motors supply.

 

[JohnW2]

When the actuator, is in the correct position, to trigger the microswitches, a diode appears in series with the motors supply.

That's really just a repeat of what you wrote before(which is something I hadn't previously heard of).

What is the diode meant to achieve, and in what sense is the motor 'stalled' when the diode is in-circuit?

 

[morqthana]

There is a reason to turn heating completely off, when one leaves the house for example, and geo-fencing will do that for you. But it is the turning back on which is the problem. Living room radiators are around 2 kW each so 4 kW in all, it does not matter how big the boiler is, or how fast it can heat the water, from 16°C to 20°C will take around an hour, so it needs to start the heating even in a built-up area in Wales at least 20 miles from home, in England 30 miles from home, and in the country 40 miles from home. But that would only work if going over 20 miles from home to start with. My geo-fencing waited for me to be about to step through the door before turning back on, basic when your phone connects to local cell.

Plan B:

If you return earlier than your predicted time, just put up with the house being a little bit chillier than you would like - put a jumper on, man up, and live with it for half an hour, you won't die.

 

[morqthana]

The main reason for wanting high power output on a combi is to allow running a bath in a reasonable length of time.

Do any of them?

 

[morqthana]

With 'all dumb' TRV's the Time clock calls for heat which the boiler provides and when all TRVs are satisfied a sensor on the return pipe stops the boiler, this is far too often incorrectly left to the boiler sensors (not so much these days). IE; the boiler overheat stat operates. – A poor system as the boiler may be constantly going through a heating and long cooling cycle and not be available when a TRV opens. Adding a room stat is complex as the room monitored could be the first to reach TRV set point so one has to work out what temp to set the stat to – yada yada yada.

With a 'zoned' system where each zone has a space stat and motorised valve, (Imagine a block of flats with a communal heating system).

With a 'full intelligent TRV' system one is effectively creating a series of zones and each can call for the boiler to provide heat and can be used in isolation.

So I'm in a room which has been designated to be at Xº because it's Y-o-clock. And for some reason, I don't want it at Xº, because I'm there when I'm not expected to be at Y-o-clock, or I've got a cold and am feeling pathetic and sorry for myself and I want it warmer. Whatever my reasons, in which of the systems you describe above is it easier and therefore better for me to adjust TRVs rather than a control on the wall?