RichardS Posted December 26, 2019 Share Posted December 26, 2019 (edited) Hello - just moved into new house and struggling to make sense of an underfloor heating system. Excuse the really basic questions. We've tinkered with the controllers (HeatMiser Slimline RF) and we think we should have heating on. The displays are active and showing the room temperatures and the little flame icon is appearing. But... the floor remains chilly. There are three zones - living area, kitchen, and a utility room. The plumbing set up is in the below photo, with my rather clueless questions / observations added. Could somebody advise me on what I should be looking for / changing before I call in an expert? https://photos.app.goo.gl/LLV8GRAFUkN3A1379 Many thanks Richard Edited December 26, 2019 by RichardS Fixed link Link to comment Share on other sites More sharing options...
JFDIY Posted December 26, 2019 Share Posted December 26, 2019 Red and blue Butterfly handled valves are correct and both open. Top 'knobs' are actuators controlled by your room thermostats, short of removing them and looking at the pin underneath when room stats call for heat. Bottom knobs are the flow adjustments for each zone, if the water in the system is clean you can see a flow indicator and these are your best clue to see if water is flowing. Have a feel of all the pipes, see where heat is getting to. Underfloor heating can take a good few hours to start to increase a room temp. Is there a pump near to this manifold, it is usual to have one, in my opinion the thermostatic mixer is not conventional and you usually have a pump/mixer combined to circulate the water locally at the manifold, blending it with a fresh slug of water from the main boiler circuit regularly. Do the temperature indicators on the manifolds ever rise? All that said I suspect it's a controls issue and a switch somewhere has been in-advertantly turned off isolating the UFH . Link to comment Share on other sites More sharing options...
JFDIY Posted December 26, 2019 Share Posted December 26, 2019 (edited) Just had another look, the pump is just visable and looks like the speed switch is between position 1 and 2, can you feel the pump running, sometimes between speeds turns the pump off. It's not normal to have actuators on the cold side of manifold, normally on the hot side to the rooms. You're also right there is a temp controller strapped to the pipe, has this been turned down. Likewise the blending valve with round blue knob might be turned down too low. Mark the position of where you start from and make some notes each time you change things, it's easy to forget where you started out and what has been tried. My first port of call is to confirm pump is running. Edited December 26, 2019 by JFDIY Link to comment Share on other sites More sharing options...
RichardS Posted December 26, 2019 Author Share Posted December 26, 2019 Thanks so much for replying... the pump doesn't seem to be doing anything at all. Will fiddle some more and report back. Link to comment Share on other sites More sharing options...
RichardS Posted December 26, 2019 Author Share Posted December 26, 2019 The pump seems unresponsive even if I try changing the switch to another setting - no sign of life at all. Adjusting the temperature controller doesn't make any obvious difference - there is an audible click as you move it up and down as it finds the room temperature, but nothing kicks into action. So I'm guessing I probably need a new pump? Better photo of pump and temp controller Thanks again, Richard Link to comment Share on other sites More sharing options...
nod Posted December 26, 2019 Share Posted December 26, 2019 While I’m no expert I ran the plumbing and electrics to our UHH and a company commissioned it but had a similar problem to yours Everything looked like it was working but no heat The guy who terminated the electrics told me he would return the following day with a heating engineer In the meantime I drained the system and refilled and everything came to life Link to comment Share on other sites More sharing options...
MikeSharp01 Posted December 26, 2019 Share Posted December 26, 2019 Is there heat anywhere in any of those pipes? Link to comment Share on other sites More sharing options...
Ed Davies Posted December 26, 2019 Share Posted December 26, 2019 Following on from @MikeSharp01's question, what sort of heat source do you have (gas or oil boiler, I'd guess)? Is it running? Does it do hot water as well? Is that getting hot? Link to comment Share on other sites More sharing options...
RichardS Posted December 26, 2019 Author Share Posted December 26, 2019 Hi - thanks all of you for further replies, particularly on Boxing Day. It's an oil boiler, and the upstairs rooms and a couple of the downstairs rooms have conventional radiators. They're working fine, and we have hot water, etc. So all working except for these three areas which have the underfloor heating. As for where the pipes are hot, please see latest photo - red lines = very hot to the touch, blue line = no obvious heat. https://photos.app.goo.gl/uoMPRRhNNvVZfBeDA Richard Link to comment Share on other sites More sharing options...
dpmiller Posted December 26, 2019 Share Posted December 26, 2019 Assuming the actuators are actually opening, the temperatures are as one would expect. If you're electrically-savvy I'd be checking for 240v (or possibly 24v) to the actuators... Link to comment Share on other sites More sharing options...
RichardS Posted December 26, 2019 Author Share Posted December 26, 2019 Thanks @dpmiller Electrics: I know one end of an AA battery from the other, that's about it. Should the pump be making any noise? It seems completely silent. Richard Link to comment Share on other sites More sharing options...
Declan52 Posted December 26, 2019 Share Posted December 26, 2019 This might sound a bit obvious but have you tried hitting the pump a gentle tap a few times when it is running. You should feel vibrations when it's running. Link to comment Share on other sites More sharing options...
dpmiller Posted December 26, 2019 Share Posted December 26, 2019 pumps should be as near to silent... hold a screwdriver between your ear and the pump, you *might* detect a faint hum but more likely a slight hiss from the bearings and water flow. Link to comment Share on other sites More sharing options...
Ed Davies Posted December 26, 2019 Share Posted December 26, 2019 Could just be that the pump has seized. If it has I think it's probably on its way out and will need replacing eventually but you might be able to get it going for a while: Link to comment Share on other sites More sharing options...
JFDIY Posted December 26, 2019 Share Posted December 26, 2019 I'd say pump is fairly likely, you show on the diagrams with red lines that the manifold is getting warm, for any warmth to be there, then there must be some flow of hot water (driven from the pump at boiler). It can only flow if one or more actuators on the manifold is open. The manifold pump, if not rotating, is causing an obstruction and flow through the UTH pipes will be low. Can you feel any warmth on the small pipes that go into or out of the floor, with the zones on and left for half an hour or more? If you can change a light fitting then you can check the pump power supply. Either test with a multi-meter if you have one and are comfortable using it, if not, isolate all power, disconnect the feed cable and wire it to an old light fitting with a low wattage bulb. If you then turn the heating on the bulb will come on when power is sent to the pump. Likewise you could wire the pump just to a 3-pin plug with 3A fuse fitted to check the pump in isolation. If the pump runs then turn the heating on and see if you get heat in the floors. Link to comment Share on other sites More sharing options...
RichardS Posted December 26, 2019 Author Share Posted December 26, 2019 A little tap and the pump seems to be humming ever so slightly whereas it seemed very still before. I also noticed that the HeatMiser controllers both needed recalibrating - when I bought in another thermometer I realised they seemed to be overstating the room temperature by 2-3 degrees. Have now reset them. I think it may be sorted, but if not will report back in the morning. Thanks so much to everyone who chipped in... Richard Link to comment Share on other sites More sharing options...
Temp Posted December 27, 2019 Share Posted December 27, 2019 The grey thing you marked "Some kind of thermostat" is just that. Its intended to limit the max floor temperature to avoid damaging some floor coverings or burning feet. Check its not set too low or the pump won't run. Somewhere around 45-55C should be OK. Link to comment Share on other sites More sharing options...
RichardS Posted December 27, 2019 Author Share Posted December 27, 2019 Bingo. All working well. Thermostat set to 50C. Thanks again to everybody. 1 Link to comment Share on other sites More sharing options...
Declan52 Posted December 27, 2019 Share Posted December 27, 2019 15 minutes ago, RichardS said: Bingo. All working well. Thermostat set to 50C. Thanks again to everybody. Do you mean the water going into your ufh circuit is set to 50C as that is really high. Link to comment Share on other sites More sharing options...
RichardS Posted December 27, 2019 Author Share Posted December 27, 2019 Was responding to "Temp's" message that 45-55 would be about right? The control marked on my original photo. https://photos.app.goo.gl/LLV8GRAFUkN3A1379 Link to comment Share on other sites More sharing options...
Temp Posted December 27, 2019 Share Posted December 27, 2019 Yes the blue mixer sets the floor temperature, the grey stat is a safety backup in case the blue mixer fails - at least that's how mine works. Link to comment Share on other sites More sharing options...
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