Fitting a Vailant VR10 NTC to a Megaflo Cylinder

[afhussain]

Hello people. I wonder if someone can help me. I have a Vailiant system boiler connected to a Megaflo unvented cylinder. I have the Vailiant 360f wireless programmable room thermostat. This is connected via a VR 65 control unit.

Everything else seems to work fine but I can not get the on demand hot water top up to work. I press the 'F' key four times, the tap symbol appears on the display but the water does not heat up.

I have done a search on the web and it seems that the reason for this is that the VR65 unit needs to be connected to the VR10 NTC thermostat and not the standard thermostat that is on the hot water cylinder.

I have checked the box of bits I have left over from the installation and there is indeed a VR10 NTC in there.

The VR10 NTC is normally fitted to a dry pocket on the Vailiant UniStor cylinders. I am assuming that the Megaflo does not have this dry pocket for me to connect the VR10 NTC to.

Someone suggested that they just cut away a small section of foam on their standard cylinder, and attached the VR10 NTC using some heat transfer paste and then covered it up with silicone.

I looked at my cylinder and it has a plastic/metal coating on the outside. I assume there is foam under this.

My question is has anyone ever fitted the VR10 NTC to a Megaflo cylinder before and would you advise it. Also how easy is it going to be to cut a section of foam out so that I can fit the VR10 NTC thermostat on the inner metal tank?

At the moment if the water goes cold we have to change the scheduled time the water is due to come on at.

Thanks

 

[simond]

You can normally squeeze the VR10 probe down the dry pocket in the cylinder.

We dont fit Megaflos (due to the design defect they disingeniously promote as a benefit, the 'floating baffle') so I haven't fitted VR10 in one, done it with plenty of other cylinders though.

If you are going to rely solely on VR10 as the temp sensor you should be mindful that it is only approved by the UK regulations when used in conjuction with a uniSTOR or auroSTOR.

You can make matters better by wiring the HW zone valve motor via the Megaflo OH stat.

I have to ask the obvious question.... if you wanted to use the Vaillant controls why didn't you buy a uniSTOR, its a much better product than Megaflo, mainly because it doesn't dump water over the floor every two years and require new pressure relief valves.

Very few products are designed to fail, but if you read the instructions on the side of your cylinder you will find the Megaflo is one of them.