funks81

It is certainly rather different to others - but its the way that Uponor like to have it set up. Flow comes in at the thermostatic valve - which has a remote sensor pocket - just above the pump. The lock shield on the top rail (just before the return) is partially closed forcing most of the flow around the UFH circuits.

Hi John, I didn't get notified about your response - hence the late reply!! Yes - there are pipes connected - but they've been terminated after about 50cm. Not entirely sure why it was done this way!!!

Regarding the first point about running it on the manifold side of the TMV - I presume in normal operation the Willis heater should cut out once it reaches it set temperature - say 35C. Obviously the floor overheating only becomes an issue should the inbuilt thermostat fail. I'm wondering if I got the electrician to fit a pipe thermostat as a backup in the event of the inbuilt thermostat failure - would there be any other reasons not to install this side of the TMV?? Obviously makes the plumbing much simpler if it could be installed here!!!

I am considering adding a Willis heater to my UFH in order to take advantage of the cheap overnight Go Faster rates. I have come up with two possible options: I have an unused port on the manifold and was wondering if there was anything stopping me plumbing the Willis heater directly into this. (It feels wrong - but can't quite work out why!!) Second option is to put the Willis heater onto the heating return. The possible problem with this is that my flow and return are 22mm and I believe the Willis heaters all have 15mm fitments. Would it be okay to run the Willis heater in parallel with the existing 22mm return? (I haven't got room in my CU for 2 x new circuits - as I see people have previously used 2 x Willis heaters in parallel). I don't think the output from the Willis heater is going to be great enough to replace the oil boiler - and I only intend to use it overnight during the cheap rate and revert to heating using the oil boiler during peak periods. The oil boiler would be switched off during these times. The heating is an open vented system. Happy to do the plumbing myself - but would get an electrician to connect to the CU.

Thanks John Great to know about the buffer - does that tank look suitable? The electric would only be used overnight during the cheap Octopus Go period (contactor and smart plug on boiler to turn off during this time) We do have a large number of thermostats in the house - but the way we use the house means we only heat rooms as we need them - its rather costly to heat the whole house all the time.

I am considering fitting a small approx 140l buffer tank on to the return of my central heating in order to prevent short cycling of my Grant oil boiler whilst only 1 or 2 UFH circuits are operating. I was thinking of using something like this - https://www.tradeplumbing.co.uk/gledhill-144-litre-economy-7-direct-cylinder.html?gclid=Cj0KCQjwguGYBhDRARIsAHgRm49cqWJ9bSAitZW9rcKBsAKQDGxN14qVeWD6VCLC4GFDaULEiV_43VcaAqoXEALw_wcB I am hoping that this will prevent the short cycling by increasing the volume of water in the system. I also figured that overnight I could use my Octopus Go cheap rate to run the UFH. In order to maintain boiler return temps I was going to fix a thermostatic mixer valve onto the heating return (the Grant boiler asks for a minimum of 50C return temp). Any comments on the feasibility of this?

We have a multi zone open vented heating system powered by an oil boiler with about 70% UFH downstairs - the rest of the downstairs and the whole of upstairs is radiators. I am considering fitting a buffer tank (direct unvented cylinder) on the heating return to the boiler, as it does often suffer from short cycling, because at times only 1 small UFH zone is calling for heat. I am also contemplating using an immersion heater to heat this tank overnight on my cheap Octopus Go Faster tariff. 1. Does this buffer tank require a vent or is it considered to be the same as putting another radiator into the system? 2. I haven't yet done any calculations for what size of buffer may be required, however, I was thinking of going fairly large - around 300L in order to take advantage of the overnight electricity. Apart from the heat losses - are there any other downsides to this? 3. What are the disadvantages to plumbing on the return to the boiler? I've seen a lot of diagrams comparing two and four pipe configurations - but not simply plumbed into the return.