Grant Vortex Eco & Honeywell CMt927

[LastDon]

Evening all, well after much searching and interesting reading I have resorted to my first post.
Just to be clear, my plumber is fitting my boiler but I get the impression it has been a little while since he fitted one, so I have a few questions.

The boiler is a grant eco vortex utility standing boiler with a sealed system kit.

We have bought a Honeywell CMT 927 and two motorised valves V4043H.

Now plumber said that room thermostat is in the CMT 927; I get this!

However, I am not clear on whether I need a cylider thermostat; he thinks not? Any thoughts?

Also, the CMT927 appears to be solely for controlling room temperature (central heating on/off time) is this correct? How should I therefore control the switching on and off of the hot water. The wiring diagrams indicate a "programmer" is needed, so do we need something over and above the CMT927 to control when the water comes on......or is it instant because it is now a sealed system?

Thanks
Anthony

 

[doitall]

Is he Oftec registered for starters, or are you going to be left in the muck.

Of course you need a programmer, and a room and cylinder stat. the cmt 927 is a programmable room stat so covers half of the problem.

You would need something else to control the DWH, in fact looking at the manual I don't think the CMT927 is a good choice.

Strangely enough we were talking about skills shortages earlier on this evening.

 

[Goldberg]

Do you want to be compliant with the Building Regulations and keep your fuel and maintenance bills down?

If so, buy a dual-channel programmer and a cylinder thermostat.

If not, get ready to turn the boiler thermostat up and down several times per day to regulate the temperature of your stored hot water, and to replace the cylinder and pipework when it becomes scaled up as a result of overheating the water.

 

[LastDon]

Goldberg & Doitall, many thanks for your reply.

Goldberg: We moved into this 1970's house two years ago had to replace the cylinder and pipes between the boiler and cylinder....it didn't have a cylinder thermostat then and doesn't have one now so probably explains why the cylinder started leaking and pipes silted up! I'll get back on to Plumbnation who supplied the CMT927 as they advised it was all that was necessary.

Doitall: Plumber is not OFTEC but is utilising a colleague to commission and sign off.

Goldberg/Doitall, Any suggestions on a good choice wireless room thermostat and hot water programmer combination?

Thanks Anthony

 

[Goldberg]

it didn't have a cylinder thermostat then and doesn't have one now so probably explains why the cylinder started leaking and pipes silted up!

No - the primary circuit in an indirect system doesn't scale up, but if it wasn't chemically protected against corrosion then they will eventually block with magnetite and rust.

I'll get back on to Plumbnation who supplied the CMT927 as they advised it was all that was necessary.

Moral - don't take advice from a merchant. If they knew enough to be heating engineers then they wouldn't be working in a shop.

Goldberg/Doitall, Any suggestions on a good choice wireless room thermostat and hot water programmer combination?

I can only think of one at the moment, which is this Danfoss product:
http://www.heatingcontrolsonline.co.uk/danfoss-randall-wireless-pack-p-264.html

It isn't cheap, but whatever you find will be expensive, so I would be asking myself whether or not I really need the hot water program to be wirelessly controllable.

If you don't, then you could buy an ordinary, crude, simple, single-channel timer for the hot water and use the CM921 or CM927 as the heating programmer and room stat. If you put the timer near the cylinder then you can minimise the new wiring for the cylinder stat and its V4073. You would need to check whether or not the boiler needs a pump overrun facility, but I doubt that a big oil Vortex would do.

Before I forget to ask - is the system fully pumped (yet)?

 

[doitall]

Personally I hate wireless, they are more trouble than they're worth, just about anything and everything in the house, including TV, remote controlled toys etc effect them.

 

[LastDon]

Thanks for your replies again.

Yes system will be fully pumped when it is finalised.

Have sorted out the control components required so thanks for the direction and for one reason and another have had to mix brands (and introduce more wireless!) but all of the outputs are essentially the same:

Honeywell ST9400C 7 Day Two Channel Programmer
Drayton Digistat + RF Wireless Room Thermostat (honeywell have no stock)
DANFOSS CET B-RF + RX1 RECEIVER (room is plastered so cant get wire down for stat).

Anthony

 

[tonybhoy]

Personally I hate wireless, they are more trouble than they're worth, just about anything and everything in the house, including TV, remote controlled toys etc effect them.

No they don't Have had a CM927 for at least two years (and the CM76 before that) and it's never missed a beat, even the batteries are the orginals.

Wireless is all I fit now since about 2006 and have only had two CM 927s die on me out of about 25 and since last year it's been the WB DT10 RF optimisors that I've installed, and so far, no a single problem out of about 14 units installed.

Tony