Easy to fit? Help needed......

[messy69]

Recently bought house, had new central heating previous, Combi Boiler upstairs cupboard, 8 radiators, 7 with Thermostatic Radiator Valves but it seems dodgy plumber didnt fit a wall thermostat to finalise the installation correctly.

Have had a look at the boiler manual (Boiler - Ideal Mini C28), shows how to dismantle the boiler and locate the "External controls terminal block" - has three individual connectors described as 1,2 & 3! which is described and shown as under the "Power Supply" terminal block.

I want to fit a wall mounted thermostat in the hall directly under the boiler location so running wire down internal stud wall is not a problem.

I have looked at a downloaded installation PDF file for a Thermostat sold on Screwfix - "Danfoss RMT230 Room Thermostat" Item 22657.

Q1 - Am I looking at the right type of thermostat

Q2 - PDF file makes no sense to me how it wires up, is it 3 flex wire simply between Boiler and Thermostat and running off boilers elec supply, does it need seperate fuse etc????

I am totally lost on this so if anyone can help I would be very grateful...

 

[andy]

you wire 3C+E from stat to a connection box next to the boiler. form there run 4C flex to the boiler. the stat needs live and switched live to work. neutral is there for some digital stats etc

 

[wedge69]

As long as you know with the set up you have it is not a necessety to have a room thermostat? Fitting one will make the system more effifcient though

Does the hall have a radiator with a thermostatic valve on? Everything I have read says it is not advisable to put a room stat in the same room as a thermostatic rad.

 

[messy69]

wedge69 - I too have read the same ref TRV's not being in same room as wall thermostat as they work against each other.

The "nice" plumber has left the bathroom as a std valve so I am going to swop the TRV from the hall radiator with the STD valve in the bathroom.

Whats happening at the moment is the bathroom is being constantly heated when the boilers programmer is switched to on, all the house TRV's switch off when the correct temp is reached but as the bathroom is an open valve with no thermostat it continues to fire the boiler and draw off hot water - not economical and costly!

 

[Steve]

The "nice" plumber has left the bathroom as a std valve

They have to do this - think about it, when all the TRVs shut off, what happens to the pump???? BANG is the answer, unless you have a standard valve. A safety feature.

I think electronic room thermostats in each room, connected to a central programmer, are the answer. Then each room could be set to a certain temp, and the central programmer sees to it all. When every room has reached temperature, the boiler shuts off. It could also learn how long each room takes to heat up and cool back down, and give it heat as nessecary, improving efficiency.

 

[breezer]

lots of stats and contrloller V 1 room stat, ..........hmmmmm tough choice.

if you (the origonal poster) ask in plumbing they will tell you that it is normall for on one rad not to have a trv (as crafty1289 said)
it is known as a "bypass" system would not literally blow up, but it wouldn't do the pump any good, so by all means swop the valves around, but do have 1 with no trv

 

[Steve]

i was fantacising, breezer, about some ideal heating control system. some rooms in our house dont get hot enough, yet others get red hot, despite having TRVs in each room (except the bathroom ). A system that learns each room's characteristics and sets up the system as such, would be ideal for a situation like this.

 

[baldelectrician]

These boilers should be wired correctly, otherwise you will kill the PCB .
Get someone in who can wire boilers and heating control circuits correctly.

you can get remote control (wireless) themostat kits which are ideal for combis where you have little scope for mess.



here is a bit from the ideal manual:



Note: the switch contacts of any external programmer,
room or frost thermostat must be volt free.
Connecting a switched live feed to external controls
terminal block may be dangerous and will result in
serious damage to the boiler.

 

[philrosenberg]

Don't know if you ever sorted your thermostat, but we put in an ideal mini 24.
Got a thermostat from B+Q, volts free as required £20. Out of 20 or so they had only two stated volts free, plus we ended up at B&Q because our local plumb merchant didn't have any volts free thermostats. Don't know if they are particularly unusual or something, butI wouldn't assume that just any thermostat is fine.

 

[tim-spam]

Be careful with putting a TRV on the bathroom radiator. Some boilers require a bypass circuit to allow the pump to run on for a few minutes after the boiler cuts out - this is to prevent boiling within the boiler and allow the heat exchanger to cool down progressively. Quite often, it is the bathroom radiator that is used as the bypass, and if this is the case, a TRV must not be fitted. In fact the radiator should be fitted with two lockshield valves to prevent it from being turned off.