Hi all, we bought a house 3 years ago that has underfloor heating on the ground floor but the way it has been installed does not seem to conform to any of the accepted standard. It has a newish oil boiler that is running the UFH temp at 75 (yes I know that is too high) but the floor still remains tepid at best. It is an Uponor manifold and I have just changed the valves and flow meters and flushed and vented the circuits (there are 9 circuits). No change still tepid. However, I am wondering if the flow and return are set up correctly. The flow meters are on the bottom manifold and the valves on the top one. When starting up, the top manifold gets warm first. I know that normally, the flow meters are on the top. How can I confirm if they are the right way around please? I could easily swap them about and re-vent the system. The pump is not on the manifold but in the airing cupboard, it's all a bit weird but I am starting by sorting out the correct flow and return on the manifold. Can anyone help please? Thanks... Rob
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View the thread, titled "UFH Manifold question" which is posted in Central Heating Forum on UK Plumbers Forums.
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It might be best if you can post a few photo's of the installation?
Sometimes it helps when you've seen it.
Thanks, yes, here we are. You can see the manifold and then the pump and the thermohead centre is in the airing cupboard which is about 40 feet away from the manifold on the ground floor. I have now replaced the valves, flow meters and the thermoheads with new Oponor ones (expensive) but although the manifold and all the pipes are hot, the rooms are still tepid. The pump is going on max but I don't know what to do with that manual mixer valve underneath it.
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The manifold should be a complete with pump and integral bypass look on line and you will see what it should look like I would be surprised if has ever worked properly. https://bhl.co.uk/uponor-7-port-v5-compact-control-pack-1059848-wp88512.html
[automerge]1737561793[/automerge]
Well yes, I know that. But this is what I have inherited. I'm just seeing what is needed to make it work better. Not all manifolds have the pump and mixer valve attached, it's not completely unusual especially on an older installation, this is about 25 years old.
Can you put inentification labels and arrows on the pipework in this photo + direction of pump flow etc.
Also manifold flow and return temperatures and any flowrate readings from the flow meters.
Also exact make/model of pump and speed setting, should be able to get some idea of circ rate.
TMV setting??.
The thing beneath the pump looks like a bypass to me from the photo, not a mixer valve but I can't see it properly.
Are both manifolds hot?
Do you have more photos of the pipe runs?
Are both manifolds hot?
Do you have more photos of the pipe runs?
Yes it is a by pass but I don't know where it goes. The pipe looks headed to the boiler which is behind the wall next to it. No I'm very limited to what I can see. What I was starting with was trying to find a way to confirm which manifold part is the flow and return as I suspect the valves and flow meters are on the wrong ones. The upper manifold part is the one that gets how when it starts up, which leads me to believe that that is the flow one but that has the valves in it not the flow meters.
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Well, this is the problem, I don't know any of that and that is why I'm trying to analyse it by starting with identifying the flow and return manifolds because I suspect the flow meters and and the valves might be the wrong way around. The pump in the photo flows from top to bottom and that valve on the by pass below is closed. I've set the pump on to auto now, which is what the manual says for underfloor systems, so it is spinning at about 5. The flow meters are all equal on 2.5. Temp settings though..... no idea, there are no gauges on the setup. The property is a converted barn so the distance from where the pump is to the furthest loop in the dining room is over 100 feet, so I think it's no wonder that the dining room in particular is always cold.
I wouldn't go off numbers on pumps to be honest. Fancy modern pumps work well if everything else is well.
The one that gets warm first will be flow.
Uponor will tell you whether direction through their valves matters.
There would normally be a mixer valve to regulate temperatures on UFH. They mix return water with flow to give a set temperature. The losses through pipe runs need to be overcome which is why there is usually a dedicated pump.
There are lots of things to take into account with any heating system. I personally do not think your issue is a quick DIY fix by the sounds of it. I advise you to get someone experienced to look at it. If you are new there, it may never have worked properly.
The one that gets warm first will be flow.
Uponor will tell you whether direction through their valves matters.
There would normally be a mixer valve to regulate temperatures on UFH. They mix return water with flow to give a set temperature. The losses through pipe runs need to be overcome which is why there is usually a dedicated pump.
There are lots of things to take into account with any heating system. I personally do not think your issue is a quick DIY fix by the sounds of it. I advise you to get someone experienced to look at it. If you are new there, it may never have worked properly.
Yes thank you that makes total sense. Tomorrow I am going to seap valves and flow meters around on the basis that flow and return are the wrong way around and then see how that goes. If no improvement I will call in the experts.
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