L641B1012 pipe thermostat

[cully]

Looking for a bit of advice, forum members,
I have a 10 zone underfloor heating system and had a problem yesterday when a faulty zone actuator left the heating system working when the CM67 programmer was not calling for heat.
I want to fit the above thermostat (which I have) in the system so that when a component fails and the return flow temp reaches a max. heat (to be determined) the stat will maintain a safe temperature for the screed.
Any help appreciated
Paul C

 

[muggles]

CM67s are notoriously unreliable (and now discontinued, probably because they were unreliable). Possibly the cause of your issues rather than the actuator? You could probably wire its switch live to a pipe stat to kill the demand, but you'd need 10 pipe stats for the 10 zones

 

[Dan Robinson]

the system should already have something like this in place.

Are these 4 wire actuators?

What system is it?

 

[cully]

The problem wasn't the CM67 as this was not calling for heat (showing no volts on my meter in the junction box)
There are three master actuators (four wire Honeywell Z 100) and individually checking each one I found one "live" sending power to the Zone valve, pump and boiler. (I presume the fault is the actuator black live to red zone, which powers the pump and boiler, hence the problem
The overheat pipe thermostat mentioned above was installed, it sat between the master actuators and pump thus not giving any protection to the system.
So what I need to do is protect the system as these components are not fail safe.
Thanks for your response
Paul C

 

[cully]

Dan, the system was supplied by "eco-hometec (Doncaster)see drg. attached

 

[Dan Robinson]

Aaaahhh no wonder it's a shyte design.

Will look at the picture when I get back to the office.

 

[cully]

Dan,
The manifold wiring diagram supplied by "Eco" was what I used to build up my drg as e-mail (don't ask why the pipe stat is where it is shown on the drg I haven't an answer but it's been there years)
What I intend doing is to place one wire of the o/heat stat with the orange wire of the zone valve in position 1 (on my drawing) and place the boiler wire with the second stat wire into position 2
Then fit the o/heat stat on the manifold return pipe and set it at a temperature just above that seen when the programmer is satisfied
Is there better protection control available for this situation?
Thanks again
Paul C

 

[Dan Robinson]

Dude - the whole thing looks a mess. Personally I would rip the lot out and rewire it with a proper UFH controller or wiring centre and a thermostatic blending valve or even an electronic mixer.

 

[cully]

Dan,
The Eco manifold wiring diagram that I posted was the "norm" back in the year 2000 when I installed the UH system, I can see the benefits of today's wiring centres but my system has been trouble free over that time so there has been no need to upgrade.
The water system has all the features, blending valve, etc. that todays systems have so again why change?
The problem that I am addressing is that some components are not "fail safe" and I want to put in place something to protect the screed.
The boiler (Man Micromat) has two water systems DHW 80deg and a modulating central heating running up to 55deg using an integral divertor valve, is there a potential screed o/heat from the DHW?
Actuators are not fail safe (hence this thread) what about Reliance blending valves, zone valves etc?
How do todays installed heating systems protect the screed?
Paul C

 

[simond]

I take it that the MAN boiler is using the low temp output to run the UFH without a blending mixer on the UFH manifold?

I assume that you are worried that the UFH blending mixer ((if fitted) or the boiler temp regulation could fail thus cracking the screed?

Simply wire a pipe stat to interrupt the two port zone valve brown wire. Then if the manifold gets too hot, it'll drop the source of temperature.

MAN boilers weren't very reliable and most have gone to landfill now, it would be a mistake spending too much on a design which is arguably obsolete.

 

[Dan Robinson]

That ecohometec lot had a lot to answer for. I'm sorting out another of their abortions at the moment.

Must have been one of their last thank god. I've had to take on around dozen or so of their victims.

 

[cully]

The Man boiler is using a low temp output and the system also has a Reliance blending valve but I will fit the overheat thermostat as you state.
Thanks for the interest
Paul
ps, in the event of a problem with this boiler (28kw htg 36kw DHW) what would be a good alternative to replace it with and would it need any additional components ie, divertor valve etc.
Thanks again

 

[Dan Robinson]

Atag Q series will do this more or less it off the box.

 

[trish.2rd]

Hi I know this thread its a bit old but I was sooo excited to see it, we moved into a house last year with a heating system none of our local plumbers seem to have heard of (we are Scotland) we have a Micromat EC 31/36 Boiler, a SMART hot water cylinder, and Honeywell CM67 programmable Theromstats, one for upstairs and one for down stairs. All supplied and fitted by ECO Hometec. The whole system has been the only thing that has caused us any problems since we moved into the house, it doesnt help that most of the instructions manuals are in german. We also have honeywell pipe thermostats fitted to pipes supplying what I thought was heat to the underfloor system both upstairs and down stairs, although I think this may be the hot water supply now (it could do both). Our current issue is as follows, my husband put a pair of trainers on top of the hot water tank to dry a couple of weeks ago not realising there was a thermostat there which he must have moved to MAX and we had our hot water supply on 24/7 for about 10 days until I managed to get help via email from a firm in England. He advised me to move the thermostat from MAX down to between 3 and 4. However we have our boiler set at 60Deg for water, can someone tell me if between 3 and 4 on the cylinder thermostat is the right setting as the water does not seem to come on at the allocated time now as set on the Honeywell Thermostat. Also can someone advise me what I should have the pipe thermostats set to also. Sorry if that was a long way for a short cut to get to the question.

 

[Dan Robinson]

The temperature range is 50 to 95 degrees, but as intimated above, that lot were a bunch of charlatans and what the stat is for God only knows.