We’ve misplaced our wireless room thermostat! How do we turn the heating on?

Ectophile

There's always the option of buying a new thermostat from someone who can offer a fast delivery.  Then go through the process of pairing the new thermostat with the receiver.

TELLIT01

Ectophile said:

There's always the option of buying a new thermostat from someone who can offer a fast delivery.  Then go through the process of pairing the new thermostat with the receiver.

I was also going to suggest that option.  It's a guaranteed way to get the original to reappear - the day after the new one arrives.

ChasingtheWelshdream

It most certainly is, and if I am going to do that, then I think I will bring forward a Hive/Nest option (still researching) so I only buy once.

However, I am concerned that there could also be an issue with the boiler itself.

I got it to override and turn on a couple of times. If the temperature was set to 70. It wouldn’t get above 43-44 degrees, then rapidly drop a few seconds before the receiver light turned off.

I tried lowering the temperature to 50, and it stayed on much longer (5-6 minutes, all rads beginning to warm). Then as before, the temperature display, rapidly dropped just before the override light went off again.

Does that still indicate an issue with the receiver, or something more sinister on the boiler? 

Bendy_House

ChasingtheWelshdream said:

haven’t really ever checked the receiver before, but a Google tells me it should flash green when pairing the thermostat and red when there is a demand for heating.

And the boiler responds, but then goes off again after a minute or so? Is the red receiver light still on?

Nope, the receiver light goes off. And won’t turn back on again, the button won’t respond.  Unless I turn the boiler/receiver power off and on again, which seems to reset it, but the light won’t stay on more than a couple of minutes at most.

Yes, the flow pipe warms as well as the closest radiator flow pipes. I have opened TRVs fully and set boiler temp to max heating. And topped up the pressure a little. 

Thanks, I tried this. Heating fired for a couple of minutes then went off again.

"Google tells me it should flash green when pairing the thermostat and red when there is a demand for heating" Aren't these two DIFFERENT lights? The green one is for pairing - 'Prog' - and the RED one is CH1 - THAT'S the one that's important here.

So, are you saying that the RED one above the CH1 goes OFF by itself after a minute or so?

My best guess is, IF the red CH1 light goes off when the boiler stops working, then the 'issue' is with the receiver and not the boiler. Phew.

That then leaves the Q - what is the issue with the receiver? I can only think of two possibilities - one is that the receiver is faulty (I hope that helps), and the other is that the hidden 'stat is still shouting out at it what to do. So, you override the 'stat by pressing the CH1 button, and the hidden stat then overrides you. That would suggest that the stat is still working, and within wireless range.

Keep searching...

ChasingtheWelshdream

Yes, sorry the light I am referring to is the red override CH1 button. (I assume the prog light is green.)

And it fires up, rads warm, temp display drops and light goes out. Then won’t turn back on. (Unless I switch the power supply off/on again)

So definitely a receiver/thermostat issue rather than an expensive boiler issue? That is good-ish news. Thank you

Bendy_House

ChasingtheWelshdream said:

Yes, sorry the light I am referring to is the red override CH1 button. (I assume the prog light is green.)

And it fires up, rads warm, temp display drops and light goes out. Then won’t turn back on. (Unless I switch the power supply off/on again)

So definitely a receiver/thermostat issue rather than an expensive boiler issue? That is good-ish news. Thank you

I would say so.

I cannot think of any way that the boiler would be making the receiver shut off and that red light go out. So either the receiver is faulty and shuts off after a few minutes, or else the 'stat is still controlling it from beyond the dark veil.

I know you don't want to mess with the wiring, but there is a simple way to link the two terminals behind the receiver, and that would prove the matter fully. But, only if you are continent.

Otherwise you might p*** yourself.

ChasingtheWelshdream

Well, I don’t touch wires (I stick with the pipes 🙂), but hubby is usually confident and competent. Usually continent….

Do tell…..!

Bendy_House

ChasingtheWelshdream said:

Well, I don’t touch wires (I stick with the pipes 🙂), but hubby is usually confident and competent. Usually continent….

Do tell…..!

Ok, a look at the Danfoss RX1's instructions suggests that it ISN'T wired like more modern equivalents.

https://www.manuals.ca/danfoss/rx1/manual?p=5

It uses terminals 2 and 3 instead of the more usual 1 and 3, but hey.

TURN OFF THE POWER. Make sure the boiler and the RX1 are 'dead'.

Look at the bottom of the RX1 - you should find two wee screws there. Slacken them, no need to undo them fully. You should find that the RX1 pulls away at the bottom, pivoting upwards around its top. It should then lift right off.

You are now looking at the wiring backplate. You should see 6 terminals, probably four of them with wires:

Left to right - Neutral (don't touch), Live (don't ditto), '1' (blank? don't ditto), '2' ( a wire), 3 (a wire), 4 (blank?) Don't ditto any of them.

Ok, possibly there's also a link between L and '1'? Take a photo and post it on here for confirmation.

Ok, to make the boiler come on for CH, you need to link terms 2 and 3 (that's what the receiver does when it's 'on'). A short piece of solid-core electrical wire, insulation removed from the end 6mm, and pressed in to the corresponding terminal slots at the very top should do - see the metal 'slot' connectors that engage with pins on the RX1? Cool. Bridge 2 and 3.

Turn the boiler CH control (radiator symbol) to 'off', and turn the power back on. The boiler should 'light up' but not come on, at least not for CH. Now turn the CH control up - it should fire, and provide CH water.

To turn it off, either turn the timer to 'off', or else turn the CH control on the boiler back down to 'off'.

Bear in mind that some of the exposed terminals are 'live', so this is really a 'test' to confirm that the boiler is ok. Replace the RX1, or cover the backplate if the RX1 is kept off.

Bendy_House

This gives you the required info: https://www.diynot.com/diy/threads/replacing-danfoss-rx1-with-hive-2-receiver.491895/

The wiring of the backplate between the RX1 and the Hive (and others) is slightly different. But don't worry about that at the moment.

This shows the two terminals that you link to make the boiler fire up for CH. If you bridge these two, and have the clock timer 'on', the boiler SHOULD come on and stay on. If you want to test if the boiler itself is ok, that's the way.

If you want to keep the boiler running for CH, then you can keep the link there, and control the boiler output temp up and down, and turn the boiler on and off using the clock 'timer' switch. BUT, you'd obviously need to protect the exposed backplate and make it safe.

You can wire-in the link too - just slacken the terminal and slip in the link wire on the other side of the screw to the existing wire. Tighten. Repeat with the other one. But I am aware you might not be happy doing this?

Anyhoo - your call - but TAKE CARE...

(When it comes to changing to, say, a Hive, then the new backplate will be wired to 1 and 3, and not 2 and 3 like the one you have - that's the only change. But that's in the future :-)  )

Oh, and ignore that user's 'CH OFF' label - that's wrong. But doesn't really matter.

ChasingtheWelshdream

Thank you so much, that is super helpful, makes sense even to my mind and will reassure me what is going on. If it works then that is brilliant and will let me relax knowing the boiler itself is (hopefully OK)

I will report back!

I never touch electrics as I don’t like not being able to ‘see’ the electricity and the obvious instant repercussions of getting it wrong. As opposed to plumbing where I can see if it leaks.

Hubby is very OK with it and does most things that he is allowed to, so I will pass him the info.

Luckily it is still mild and we have a wood burner so things aren’t desperate desperate. If we can either hold off until payday for a replacement, or find the darn thing in the meantime, all will be well.