What controls for my new boiler??

[jimbo.911]

Hi, recently moved home and boiler needed replacing. Had a remeha Avanta 18 fitted and have now found out that need to replace controls.

For ease would like to fit a wireless roomstat as existing has an odd quirk of killing power to the boiler totally even if there is demand for HW. Am going to replace the programmer, pump and valves. these seem easy enough to spec but thermostat instructions talk about "volt free" and also 24v with a two wire controller.

Assume this means the on off is volt free but then goes on to talk about using a modulating opentherm controller??

So what wireless room stat would you recommend to use in the system that would wire straight into the allocated terminals on the board. Clearly wold like the most efficient route as on LPG

Thanks for your help

 

[muggles]

iSense RF

 

[D_Hailsham]

iSense RF

This is an Opentherm stat.

If you are going down that route, you must use a diverter valve (Honeywell V4044), installed and wired as show in the Remeha Suggested Schematics Book: Option 10 -Time/Room compensated Heating with Priority DHW (iSense - Digital clock).

The iSense needs to be set to 'Clock Prog' in the Settings (Menu > Settings > DHW > DHW temperature).

If you are installing a new pump, you should go for the Grundfos Alpha2 L.

 

[jimbo.911]

Thanks for the info, was a bit confused with the need if using the isense wether you had to go to the down the route of fitting the external temp sensor etc. as not sure what benefits this will have.

 

[D_Hailsham]

Thanks for the info, was a bit confused with the need if using the isense whether you had to go down the route of fitting the external temp sensor etc. as not sure what benefits this will have.

The iSense can be used with or without an external sensor.

If used without an external sensor (Room Control) it adjusts the boiler temperature according to the difference between the actual and required room temperatures. It does this by 'modulating' the boiler, i.e changing the boiler output. Older boilers had a fixed output and were either on or off.

If you use an external sensor the boiler temperature is determined by the outside temperature - colder outside means a higher water temperature and therefore a greater output from the radiators. This does mean that each system has to be 'tuned' to ensure that the required room temperature is achieved. It's referred to as 'adjusting the heating curve' which is the relationship between outside and water temperatures, and is done so that the coldest room reaches the required temperature.

If you decide to change the required temperature on the iSense it will automatically adjust the heating curve to achieve the new temperature.

The benefit of either method is that you are not heating the water any more than is necessary to achieve the required room temperature. Contrast this to the old method where the water was always heated to a fixed temperature, which it did not always reach as the room thermostat had turned the boiler off.

The saving made by using room/weather compensation can vary from 1 or 2% up to 20% (manufacturer's estimate).