CM67 Optimum Start algorithm

[Andy Hall]

It can. It can be days or even months. The only criterion is that it goes on and off.

Some fairly crude ones, and I can read at least as well as you can, the difference being that I understand what I read.....

I don't think so. Already working and there are some interesting ideas which are commercially exploitable so I won't be discussing them here as I said.

I don't need to try to be anything. I designed control systems as an honours degree project and subsequently commercially for various industries for more than 10 years after that.

.andy

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[Andy Hall]

You moved it to that discussion because you got out of your depth with respect to the CM67 by trying to be clever and falling on your face. You then proceeded o compound the issue by using your normal tactics.

Actually the discussion about snakes is quite apropos. They slither around as well.

Nope and there are two.

.andy

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[Neil Jones]

This only goes half way, though. With a simple wall stat I can't say that I want my bedroom at 18C between 10pm and 11pm, and 20C between 6am and 8am, and that I don't care what happens in between as long as it doesn't go below 5C.

[Andy Hall]

Quite. I would be surprised if the valves are south of £100 a go.

I've been developing a system which includes this type of functionality plus a great deal more. There are some commercially exploitable aspects, so I don't want to expand on the details as yet.

.andy

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[IMM]

Not so.

But you have absolutely no experience whatsoever of them.

Not so.

Such as what? Electric valves on a rad with a central controller? Not new at all. The Honeywell RF system is the best in principle as there is no wiring. Or are you going to sell snake controllers?

This have moved on since then and you are clearly way behind.

Who?

[IMM]

Andy you are clearly bitter and twisted. You never thought of this brilliant simple method

Andy, you being a snake aficionado will know about slithering from close quarters.

[IMM]

Then replace the simple wall stat with a wall stat/programmer. Some of these are now quite cheap and well specced. So, one single channel timer for the DHW and only wall stat/programmers. But I would have a single channel timer on the CH to make sure all the CH off, a master controller. This could be programmed to be on for a few hours a day when on hols. For frost protection, you could have a switch that only allows the hall stat/programmer to operate and all zone valves are powered full open bypassing the room stat/programmers.

This is a good, relatively simple, and very effective solution for a new installation, using ready made off-the-shelf parts, that any heating engineer can understand, but may be disruptive to re-divert the existing pipes.

[IMM]

Just give us the functionality, not the details. I'm certain it has already been thought of.

[Neil Jones]

controller.

existing

OK, so I've got £23 for the zone valve and £30 for the programmable stat, per room. Plus wiring to supply each stat, and replumbing, and redecorating. I don't think your suggested system is realistic as a retrofit, in my situation, at least.

All of a sudden, Andy's suggested £100 per HR80 looks rather more reasonable (purchase of shares in Duracell notwithstanding)...

Neil

[IMM]

They are available for far less than that.

That is what I pointed out. If renovating then this is a good solution.

[Neil Jones]

channel

Are they?

solution.

No, what you actually said was "A real cheap solutions is to create a manifold and have all the rads flows off this. Each rad has a 2-port zone valve (cheap at £12 at BES) and each rad hasn electronic wall stat."

It was once I started to look into your suggestion that you added the caveats that meant it wasn't a solution at all, nor was it "real cheap".

Neil

[IMM]

I have seen them around for £20-25. Screwfix do one for £25, not sure if the spec fits your needs though.

What I also said was:

"This is a good, relatively simple, and very effective solution for a new installation, using ready made off-the-shelf parts, that any heating engineer can understand, but may be disruptive to re-divert the existing pipes."

What do you mean it is not a solution? What do understand by "solution"? Cheap? At max £50 per room (£24.68 per zone valve: £25 for stat = less than £50). If ordering 10 of each you may get a discount. Compare that to the Honeywell RF method.

As I said..."This is a good, relatively simple, and very effective solution for a new installation, using ready made off-the-shelf parts, that any heating engineer can understand, but may be disruptive to re-divert the existing pipes."

[Neil Jones]

existing

You said this after I pointed out your 'solution' wasn't going to fly, so you modified it to use programmable stats instead of ordinary bimetallic ones.

YOu haven't even found out what I want to achieve - how can you know if it is a solution or not?

I have 11 radiators. According to you, £550 is cheap?

Plus wiring, plus plumbing, plus redecoration. All these are cheap too, are they?

You said this after I had pointed out that your original 'solution' was a non starter.

Your problem, if I may be so bold, is that you propose 'solutions' when you haven't taken the trouble to identify the problem.

Neil

[IMM]

You must follow the thread, you were apart of it. I suggested "electronic" stats BTW, then with your response stat/programmers.

You were on about individual control of each room if I recall rightly. If you want individual control of each room in temperature and time, and temps at set patterns over a day, then this is very cheap solution. VERY CHEAP!

For that solution? with functionality? buttons!

You must focus. I clearly made the distinction new build/renovation and existing.

It was a starter, then you said you wanted time control and different temp throughout the day for individual rooms. What do you want? Me to pay for a CM67z system for you and fit it over the weekend too? My God!

What an ungrateful sod!

What is your problem? The technical one, it is clear you have a personal one.

[Neil Jones]

"electronic"

My mistake. Are electronic room stats cheaper than bimetallic ones?

Your "real cheap solution" didn't do this. Ergo it wasn't a solution.

Which is relevent to me how, excatly? Am I buliding a new house or renovating?

re-divert

This is a good start - ask me what I want first, before suggesting a 'solution'. I am glad you have learned something today.

Not at all.

I have gas fired central heating with a non-modulating conventional cast iron boiler which is rated at about double the worst-case heat loss for the house. I have a programmable room stat, with TRVs on 10 radiators and one bypass.

How much would it cost to add individual time/temp control to the system with a view to increasing efficiency without the disruption of moving or reconfiguring pipework?

If you recall, I mentioned that I had been looking at the CM67z and HR80 solution yesterday becasue it appeared to do what I wanted, although at the price indicated I would want more - interfaces to house control system, that kind of thing.

Neil

[Set Square]

Hi Neil,

The CM67z sounds interesting to me as a way of retrofitting some measure of individual room control to an existing system without a lot of plumbing and wiring changes. The main drawback seems to me (apart from the batteries!) to be the fact that each CM67z only controls 2 zones. So if you have (say) 10 rooms, and want each room to do something different by way of temperature profile, you need 5 CM67z's - which could get a bit expensive.

I think that if I were to upgrade my system - which is similar to yours except that I haven't got any TRVs - I would probably fit a 2-port zone valve in the feed to each rad, and have each of these controlled by a programmable room stat. [Ok, I would need 10 stats, but they could be a lot less exotic than a CM67z]. Installing zone valves would not necessitate converting to a manifold system (contrary to IMM's inference) as long as you can get at the feed pipe to each rad in some suitable location. Bringing them all together in a central point would simplify wiring up all the volt-free contacts on the zone valves to control the boiler - but is by no means essential. In my case, at any rate, all the zone valves could be under the upstairs floorboards, and the only exposed wiring would be that going to each room stat - which I would cover with small section white square trunking until the room is next decorated, when I would chase it into the plaster.

[Andy Hall]

Then it won't be as accurate.

Glad you put that in double quotes.

I can understand that.

.andy

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[Andy Hall]

From the data sheet, the adjustments are quite crude in their effect simply because the device being controlled is crude in nature.

As I said, there are some commercially exploitable things in what I'm doing, so I won't be going into detail

Basic principles of control mathematics don't change. Their practical application certainly does and I have some interesting new concepts that I am developing.

I wouldn't reveal information like that any more than you would.

.andy

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[Andy Hall]

Far from it. This is such an old and outdated way of controlling actuators that I am surprised that there are still products on the market using it.

.andy

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[Andy Hall]

Wait for the personal insults......

.andy

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