Search results

Hi I’m using a VR65 on my 428 and you should hopefully find enough info on the thread below to get started. https://www.diynot.com/diy/threads/vr65-vr66-for-hw-flow-temp-control.494071/

Can you post photos of the thermostat and the wall box near the boiler?

That’s useful information. When I started using a Vaillant ebus controller to handle the DHW side of things it did get rid of the startup burn which used to be at about two thirds of full power and sometimes caused the boiler to trip. I hadn’t realised that using the official Vaillant room...

The cheap Honeywell ones (eg on Screwfix website) would be ok for this. They are really intended for 240V mains connections but will work reasonably well as a simple switch with only 2 wires connected. https://www.screwfix.com/p/honeywell-home-1-channel-wired-mechanical-room-thermostat/696fv...

Sounds like the HW ON signal isn’t coming out of the programmer, or it is somehow lost on the way to the cylinder thermostat.

Sounds like the hot water flow switch thinks a hot tap has been turned on and is firing up the boiler. If it has been like this ever since the repair, you should really ask whoever did the work to come back and sort it out.

Sorry @charmOl I’m not clear whether the problem is the boiler coming on when it shouldn’t be on, or whether you are concerned about the boiler cycling. When you say Heating ON do you mean On at the programmer but turned Off at the room thermostat, in which case I’m with CBW on this one.

Try to find out exactly which cylinder you have. Post a few pictures if possible. A modern rapid recovery cylinder would almost certainly solve this problem.

From the checks you’ve made it does look as if that’s how it’s wired up. As you say, I would try providing the upstairs programmer with a permanent live and see if it all works the way you want.

Yep, many years ago I started with flexible connectors on our kitchen tap to make for easier installation. Soon changed over to copper all the way down when we saw how much the whole thing flexed.

When set for heating only, does the MA1 lever move right across to the ‘H’ position?

I’ve no experience of this but a quick Google gives the following https://www.johnguest.com/speedfit/blog/common-underfloor-heating-mistakes-during-installation/

Looks like you have already sussed this out. As you say, all the thermostat receiver needs to do in this case is act as a switch and won’t need an additional Live link because the boiler is already providing this on one of the control wires.

That’s a great saving compared to the Honeywell valves. I see they also do a 3 port for about the same price.

Unusual but is it possible the second feed is from a storage tank in the loft? Maybe leave it running for a while with the street stopcock turned off.

Is it possible the towel warmers, being poor radiators and installed with larger bore pipework, are short circuiting the system and allowing the hot flow water a quick easy path to the boiler return. I would check whether turning them off for a while makes any difference to the differential...

Yes I’m pretty sure the 5 degree arrow should be at the 12 O’clock position. Otherwise it will switch on the boiler at a much higher temperature.

Time does come into it. If you are doing work at a certain rate (ie Power) for example in joules per second, the longer you continue the more work you will do. A kW is a rate of doing work or a power of one thousand joules per second. If you do that for an hour the total energy is 3600 seconds...

You do seem inclined to stick out your neck a lot for someone who turned up here very recently in search of help.

As CBW says you could locate the nest thermostat on the wall where the old thermostat was mounted. If you can identify the two wires from the boiler that used to connect to the thermostat you can remove them and connect them to the Heatlink T1 and T2 terminals to provide low voltage power for...