Thermo replacement problems

[baggies66]

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Lets detail my system, I have a combi boiler Icos Ideal m3080, there is a programme unit by the boiler and use to be a Danfoss rnt 230 thermo in the hall, this connected by 3 wires red,blue & yellow.

I decided I wanted more control over the heat as I am in all day so thought I would replace the hall way thermo with a Salus RT500, this takes only 2 wires so doing as I was told I isolated the blue and connect the red into live and the yellow lead, I know get error messages from my boiler and looking up what they mean H1 is a flow thermistor error, now this was not happening with the rmt 230 so is it because of this blue wire?, I am not sure whether I need to look at another unit maybe the blue wire done something that the new unit does not cover for, I am not great with things like this but I thought it was a simple job that I could do without loads of expense.

Thanks

 

[BGEngineer]

The ICOS is a conventional boiler and not a combi.

Firstly lets clarify a 3wire stat and a 2wire stat

A 3 wire stat usually consists of a Common, Calling and a Neutral.

A 2 wire stat consists of just a Common and a Calling.

On a 3 wire stats the neutral is used to power a built in anticipator which smoothes out the switching of the stat by reducing the on off fluctuations.

However you should be careful as Motor On and Motor Off 2 port valves such a Sunvic use a 3 wire stat where the Satisified on the room stat is used as well as the Common and Calling in order to close the valve as opposed to a spring return. A Sunvic Motor On Motor off valve will look like a white box with no levers on it.

To be honest I dont think the problem you are having is related to changing the room stat and I think it is a coincidence. Its either going to be a thermistor problem or PCB problem. I would try the thermisotr first as this is the much cheaper option. Hope this helps.

 

[baggies66]

Thanks for correcting me I really don't know the difference, I was convinced that I needed another unit and was even thinking of maybe using another danfoss or wondered if there was any units that used the blue wire the same as the danfoss I took off?

If the 2 wire just means isolating the blue this I have done, your post has helped, I placed the old danfoss back on for the evening without any problems so not sure whether to look at a better unit or get an egineer to call to look at this thermistor.

I am loss on the motor on and motor off and is Sunvic another thermo make as I have tried to replace my danfoss rmt 230 with a Salus Rt500.

Thanks again

The ICOS is a conventional boiler and not a combi.

Firstly lets clarify a 3wire stat and a 2wire stat

A 3 wire stat usually consists of a Common, Calling and a Neutral.

A 2 wire stat consists of just a Common and a Calling.

On a 3 wire stats the neutral is used to power a built in anticipator which smoothes out the switching of the stat by reducing the on off fluctuations.

However you should be careful as Motor On and Motor Off 2 port valves such a Sunvic use a 3 wire stat where the Satisified on the room stat is used as well as the Common and Calling in order to close the valve as opposed to a spring return. A Sunvic Motor On Motor off valve will look like a white box with no levers on it.

To be honest I dont think the problem you are having is related to changing the room stat and I think it is a coincidence. Its either going to be a thermistor problem or PCB problem. I would try the thermisotr first as this is the much cheaper option. Hope this helps.

 

[BGEngineer]

To be honest I would use a Danfoss controller over a Salus any day of the week.

Your system will more than likely work like this:

Clock sends power to Common on room stat.

If the room stat is turned up this sends power out the Calling to a motorised valve.

This will in turn motor open the valve and once this is done it makes a switch sending power out to the boiler and pump to run.

A Sunvic valve is a type of motorised valve.

Just checked The RMT 230 wiring, just check this is the same as yours:

Neutral should be in 4
Common in 1
Calling in 2

So if you have the original 3 wires like this you dont have a motor on off valve.

Unfortunately most programmeable room thermostats such as the one you have purchased only use 2 wires, after searching Danfoss and Honeywells databases just for ease of installation. Unfortunately I still can not see how this would affect the boiler operation though as all it is used to so is switch the boiler on and off. Sorry I can not help any further.

 

[baggies66]

Thanks you have helped me loads, the wiring is how you stated, I think then maybe this is just some early signs that my 5 year boiler may need some attension, I am going to swap the salus over for a Danfoss anyway to see if that helps, the danfoss units are 2 wires too so I shall just keep the blue isolated.

To be honest I would use a Danfoss controller over a Salus any day of the week.

Your system will more than likely work like this: