CM67 Optimum Start algorithm

There you go. True to form.....

.andy

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Reply to
Andy Hall
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Nope. I m certain that the overall concept has not been thought of before and I am not even going to describe it in outline.

.andy

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Reply to
Andy Hall

Or ""?

PoP

Sending email to my published email address isn't guaranteed to reach me.

Reply to
PoP

3-port (mixing) valves are very commonly used in commercial HVAC controls for things like weather compensation, so I'm surprised at the difficulty being had in identifying products;-) Drayton certainly used to make 3-port valves with a potentiometer to provide positional feedback - 'Theta YB' series' valves (just found an old data sheet). As this isn't my field I don't know whether these still exist, or whether they've given way to geared stepper motor drives (which should work OK open-loop) or something else. You could also sense the temperature (error) of the mixed water and use that to control the valve position.

Interesting thread this, although it's reminding me slightly too much of Ted Horrocks's lectures...

Reply to
Andy Wade

Well I recommend 5 years in the control industry then you will.

Reply to
IMM

Very true! The 0-10 or 0-20v simulated proportional feedback control supersede these. The pot on the valve acuautor was one of the points in a whetstone bridge. I'm not sure if they are still around, Satchwell made them, and were about the last company to get out of the 1950s (British of course). Billman (Quality Swedish stuff bought out by L&G) made them and parts were available, but probably not by now. You probably can still get them. Most just replace the actuator and controller if either one fails. The controller had to be mated to dedicated valves/actuators. You could not mix and match.

Reply to
IMM

Andy, some people have to be told when they are attituding it. Do think he might have been drunk?

Reply to
IMM

system

Give an overview and I will tell you if you are going up a blind alley.

Reply to
IMM

"Set Square" ...

plumbing and

batteries!) to

temperature

necessitate

Bringing

Good point, although I'm not sure I have room under the floorboards to house the zone valves, and having them exposed in each room would not have sufficient WAF to obtain budgetary approval :-)

When I first saw the CM67z I considered 2 zones (being nominally 'living rooms' and 'bedrooms'.) Clearly if one room calls for heat the whole system will be switched on, but unless I *actually* zone the system that will happen whatever I do. Battery life looks a definite disadvantage - these valves must be making adjustements on a fairly regular basis. On the other hand it would probably be simple to use a mains transformer instead.

At the end of the day, if it starts getting too expensive I'd be better off replacing the boiler, although that is no simple job either, given the layout of the house.

Neil

Reply to
Neil Jones

I'm not really that bothered what he thinks of me...

Reply to
Neil Jones

A manifold is by far the best method all around, although not necessary.

In your case you could use CM67RFs and no wiring and re-decorating.

Reply to
IMM

As long as you don't have snakes.

Reply to
IMM

'solution'

'solutions'

Snake free zone round here :-)

Reply to
Neil Jones

Mmm. Exactly. You attended some of those?

.andy

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Reply to
Andy Hall

Very generous, but I already know what the commercial opportunities are.

.andy

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Reply to
Andy Hall

Do they have a web site?

Reply to
timegoesby

Yes, it's at

formatting link

Reply to
Set Square

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