Replacing Old Honeywell Thermostat with Danfoss TP5 - Help..

[jaq1967]

Hi,

New here.

I have an old honeywell dial type thermostat (brown and cream 70s?, I think!) and it is located stupidly near the boiler cupboard - always warm there!

I have to hand a Danfoss TP5 room thermostat I wish to replace this thermostat with, and to relocate it in another room. Is this a simple enough thing to do? The Danfoss TP5 has three connecting points at rear:

3 N/O
2 N/C
1 COM

So... what goes where???

Although the Danfoss TP5 is battery powered I see it is rated for 6(2)A, 230V 50Hz and designed for fixed wiring only. I'm a bit confused about this. Can somebody enlighten me?

Any advice welcome.

Jaq

Oh... the honeywell thermostat is (I think) an EE4 4200 3879-001 (does this make sense) There is a wiring diagram inside the outer casing and it seems 3 wires are used although there are 5 points. They are:

5 Not used
2 Blue (Neutral?)
3 Red (live?)
4 Not used
1 Yellow (Earth?)

Dunno if this helps... but that wires would I connect to the Danfoss???

 

[jaq1967]

I guess nobody knows then?

 

[EliteHeat]

What sort of motorised valves do you have? i.e. two 2-port or 1 3-port

 

[jaq1967]

It's motorised but as for the rest... no idea. I though it would be a simple case of a simple exchange.

 

[EliteHeat]

It's motorised but as for the rest... no idea I though it would be a simple case of a simple exchange.

If you think that then you might consider getting someone to fit it for you.

You are dealing with mains voltages and a volt-free relay, which will object if you get it wrong.

You are swapping a 230V room thermostat for a battery powered volt-free programmable room thermostat, these are not at all similar and it is not a simple exchange.

 

[jaq1967]

OK... maybe I am a little confused. The Danfoss is battery powered for the timer aspect of control surely??? It still nevertheless is rated for 6(2)A, 230V 50Hz and designed for fixed wiring only, so I assume that it has the mains wiring to the pump going through it to switch the pump on and off and the timer within controls this (which is battrey powered)?

So... what is it? How is it different from the old honeyweel unit - other than the honeywell isn't battrey powered and is a manual controlled thermostat?

In answer to the other question the pump is wired to is a Grundfos Super Selectric (P/N 59526609). Does this help?

Thanks again...

 

[jaq1967]

Right... got around to fitting the unit it the end and it was a doddle - following simple and safe precautions of course. Worse I'd expect is to blow the unit up but didn't think I would.

I worked out (using a tester) on the Honeywell what cables were making the loop (switch). The third is redundant in this array.

You only use 2 wires (not three) to connect the Danfoss. The Neutral (blue) connected to 2 on the Honeywell) is NOT used and is isolated. The other two wires (Live & Earth) form the loop and are connected to terminals 1 & 3 of the Danfoss unit.

Tested and works perfectly....

Thought I'd share this information in case anybody else has this question. Don't be scared to try things - just be careful.

 

[jaq1967]

In fact it was a piece of cake using a little logic and was indeed simple in the end!

 

[west4]

So you are just using the temperature control side of the danfoss... and like for the honeywell, you have a separate timer that switches the heating on and off?

 

[jaq1967]

So you are just using the temperature control side of the danfoss... and like for the honeywell, you have a separate timer that switches the heating on and off?

There is a seperate 'power' switch which goes to the Danfoss which is permanantly switched 'on'. This is fed from a timer which is disabled. I'm using the Danfoss to control the temperature and effectively switch the boiler on and off too. It works perfectly.

 

[west4]

Sounds very enterprising... so If I set my Potterton heating controller EP2002 to permanently 'on' instead of timed, and replace the ancient Honeywell Thermostat with the Danfoss, then in theory the TP5 will control the heating all the time...(and the Potterton timer attached to the boiler will still control the hot water which is on a separate circuit? (sorry for the dumb questions)

 

[jaq1967]

Sounds very enterprising... so If I set my Potterton heating controller EP2002 to permanently 'on' instead of timed, and replace the ancient Honeywell Thermostat with the Danfoss, then in theory the TP5 will control the heating all the time...(and the Potterton timer attached to the boiler will still control the hot water which is on a separate circuit? (sorry for the dumb questions)

Your setup doesn't sound bad. Remember: I'm no electrician nor boiler specialist so not familiar with what you have so treat my advice with sensible caution. For my setup I just wanted something which gave me 'more' control than the original set up of 'set temperatures' and 'set times'. The Danfoss technically suited my requirements with a choice of variable times I could set up for during the week and different settings for the weekend. It seemed logical to wire it up in the place of the Honeywell and set the original/seperate timer to be set on perminantly 'on' and have the Danfoss take control. Logically it is just a switch which is temperature controlled. The Danfoss is battery powered and NOT mains powered - be aware of this. Anyway... it works for me. I took a chance and it hasn't failed. Maybe I am just lucky??? Good luck!

 

[peter21again]

After reading this article I decided to replace my broken boiler timer and old Honeywell thermostat (same model as OP), but somehow in my excitement I ended up with a mains powered receiver for a wireless thermostat and programmer (Danfoss TP5000Si). I realised the problem as soon as it arrived. But looking at the installation instructions and the wiring diagram for the old Honeywell, I was still able to connect it up. My Honeywell thermostat contains a Live, Neutral and a switched live, so I used the live and neutral to run the receiver, connected a link wire from the live to COM on the backplate of the receiver, and the switched live to ON. The boiler is set to constant and the Danfoss now controls everything - no more getting up at 6:15am to switch the boiler on - yay!

My point is this, no need for a battery powered programmer or timer when there is power at the thermostat. I'm guessing this opens up the possible hardware solutions to more than the Danfoss now.

Hope this is of use to someone! Even more interesting,the drill hole placements from the back of the Honeywell thermostat match the drill hole locations on the new back plate, didn't even need to drill new holes....bliss!