PickaxePete Posted January 8, 2021 Share Posted January 8, 2021 (edited) Hi All, Hoping you lot can help me with an issue I'm having with my UFH. I think from reading several threads on here (and drawing parallels to my own situation) I have an idea on what the issue might be, but would like to hear from practiced experts with more than my rudimentary knowledge of UFH! Onto the issue... Setup Bungalow UFH, no upstairs. Nu-Heat installed 8-port manifold servicing 8 zones System installed about 10 years ago when the property was built. Images of manifold setup attached. Problem Two of the zones (Living Room & Kitchen) are very inconsistently warming up. They will heat up, but not super warm and take ages to do so. Anecdotally "not as hot as it used to get" according to my wife. Troubleshooting so far All zonal thermostats seem to be working ok - turning them up triggers the actuators. Actuator pins are all working as expected. Have had the actuator heads off and checked. Pump is operating as expected - can feel the difference in switching it up to II or III. Thermostatic valve is working fine - input temp on manifold is reflective of changes to the valve temp setting. Flow valves are all ok. Manifold pipes out to the ON zones are hot. Manifold pipes back in from the ON zones are warm. Manifold pipes out to the OFF zones are cold. Manifold pipes back in from the OFF zones are cold. I of the impression that this is pointing to an airlock somewhere in the system, possibly affecting the Living Room & Kitchen zones as they are the furthest away from the manifold? Any input on what else I can do / troubleshoot in this would be very helpful and much appreciated! Regards, Lee Edited January 8, 2021 by PickaxePete Link to comment Share on other sites More sharing options...
Temp Posted January 8, 2021 Share Posted January 8, 2021 Could be a balancing issue if the problem rooms are the longest loops. Link to comment Share on other sites More sharing options...
PeterW Posted January 8, 2021 Share Posted January 8, 2021 Good news is you’ve got drain valves on the manifold so you can flush the loops. It should have inhibitor in the system but if it’s 10 years old then it should be replaced anyway. Is this a gas boiler system too.?? You'll need a couple of lengths of hosepipe and some jubilee clips (don’t expect the hoses to stay on under pressure ..!) and connect the mains water to the supply and the drain off to the return. Isolate the manifold using the valves to the right of the pump so you’re only flushing the circuits. Mark all the heads and remove them - you want to manually flush the loops - and then open the flow and return isolators and push the first pin down. Open the valves on the hose ends and this should show flow through the valve and first circuit and any crap should come out. Run it for a minute - having an assistant to watch the rubbish coming out is worth it. When it is running clean then push the next pin and release the first. This will flush the whole lot and also push the air out - when you’ve done, turn off the isolators and the water, and then open the pump isolators. You may find you need to bleed the manifold after it runs for a while - that’s the white bleed valve on the top left. One thing I would note is the pressure is low - is this run from a boiler and is there an expansion tank on the system ..? When was it checked last ..? Link to comment Share on other sites More sharing options...
Rich123 Posted January 8, 2021 Share Posted January 8, 2021 Hi I think I would blow the pipes through with water , that will deal with any air locks and possibly any sludge build up. possibly the thermal actuators are leaking , they rely on expansion of the fluid so it’s possible that there is a slight loss , try removing them to see if the system operates better. Link to comment Share on other sites More sharing options...
ProDave Posted January 8, 2021 Share Posted January 8, 2021 But the flow meters are all showing good flow around all pipes. And did I read that right 55 degree flow temperature ???? If the rooms are not heating up at that then I am at a loss to know what is wrong. Where are you and how cold is it? Link to comment Share on other sites More sharing options...
Rich123 Posted January 9, 2021 Share Posted January 9, 2021 11 hours ago, ProDave said: But the flow meters are all showing good flow around all pipes. And did I read that right 55 degree flow temperature ???? If the rooms are not heating up at that then I am at a loss to know what is wrong. Where are you and how cold is it? Yep,I did think that also but if it was working before then something has changed either with the system or the room. micro bubbles can be an issue but it’s not something I have encountered on under floor heating. Link to comment Share on other sites More sharing options...
PickaxePete Posted January 9, 2021 Author Share Posted January 9, 2021 Thanks for all the feedback. I'll try to answer questions where they have been asked: "Could be a balancing issue if the problem rooms are the longest loops." The rooms where this is happening are likely the longest loops, however this system has been operating for 10 years so I'm hoping it was installed and balanced correctly on installation! Can a system come "out of balance" over time? How would I troubleshoot this as a potential issue? "One thing I would note is the pressure is low - is this run from a boiler and is there an expansion tank on the system ..? When was it checked last ..?" It is run from a boiler and there is an expansion tank installed. I noticed the pressure gauge too. We recently had a local heating engineer in recently to have a look, and he thought the system pressure looked ok, although the pre-set on the dial seems to indicate it's under where it should be. Not sure he was entirely accurate.... In your experience, should the pressure in the system be higher? The gauge on the expansion tank is set to 1 bar (cold). "...possibly the thermal actuators are leaking , they rely on expansion of the fluid so it’s possible that there is a slight loss , try removing them to see if the system operates better." You mean the actuator heads? By removing these it should open fully (by default) and thus troubleshoot if this is an actuator issue? "...and did I read that right 55 degree flow temperature ????" Yes - I think the local heating engineer that came to look turned it up from 45' to 55'. Based on your apparent alarm at this, I've turned it down! I am assuming that this temp is higher than you might expect? "Where are you and how cold is it?" Essex (East Midlands), so definitely not as cold as the Scottish Highlands, but as the nights are fair drawing in, you can feel the cold in the large rooms when the system is not operating. I've got some other questions about @PeterW's response, but I'll put those in a new response. Thanks! Lee Link to comment Share on other sites More sharing options...
PickaxePete Posted January 9, 2021 Author Share Posted January 9, 2021 16 hours ago, PeterW said: Good news is you’ve got drain valves on the manifold so you can flush the loops. It should have inhibitor in the system but if it’s 10 years old then it should be replaced anyway. Is this a gas boiler system too.?? You'll need a couple of lengths of hosepipe and some jubilee clips (don’t expect the hoses to stay on under pressure ..!) and connect the mains water to the supply and the drain off to the return. Isolate the manifold using the valves to the right of the pump so you’re only flushing the circuits. Mark all the heads and remove them - you want to manually flush the loops - and then open the flow and return isolators and push the first pin down. Open the valves on the hose ends and this should show flow through the valve and first circuit and any crap should come out. Run it for a minute - having an assistant to watch the rubbish coming out is worth it. When it is running clean then push the next pin and release the first. This will flush the whole lot and also push the air out - when you’ve done, turn off the isolators and the water, and then open the pump isolators. You may find you need to bleed the manifold after it runs for a while - that’s the white bleed valve on the top left. One thing I would note is the pressure is low - is this run from a boiler and is there an expansion tank on the system ..? When was it checked last ..? Thanks for the detailed reply. I'm kind of resigned to performing a flush, which will give me piece of mind that it's been checked and re-filled and any crap / air is removed and cross this off the troubleshooting checklist. I'm going to gear up to do this one weekend. Some questions though, if I may to make sure i';m understanding correctly? I've attached an image to confirm the components you are talking about before I break something expensive! Can you confirm: Top yellow circle is the flow / supply (water in) Bottom yellow circle is the return (water out) Blue circles are the manifold isolation valves Green circles are the flow / return isolation valves "Mark all the heads and remove them - you want to manually flush the loops - and then open the flow and return isolators and push the first pin down." Remove all the actuator heads? They are already marked from installation, but I'll take a photo record to make sure I have a reference. I thought by removing the heads, all zones would becomes open? By pushing the pin down would the close the zone? "It should have inhibitor in the system but if it’s 10 years old then it should be replaced anyway" How would you get inhibitor into the system? Is this something a layperson could do or is special tooling required? "You may find you need to bleed the manifold after it runs for a while - that’s the white bleed valve on the top left. " So, after the flush /re-filing, I should bleed any air lef tin the manifold. Does the valve just turn to belled or do I need to un-screw it? I am assuming I don't need to touch the flow valves? Regards, Lee Link to comment Share on other sites More sharing options...
PeterW Posted January 9, 2021 Share Posted January 9, 2021 I’d expect those actuators are spring closed so take one off and see if the flow stops. If not you may have to remove an actuator one at a time. All your circles are spot on ..!! Inhibitor... quickest way is whilst it’s all isolated, close the top and bottom drain valve and then remove the white air vent screw. Get one of these from Screwfix in a standard skeleton gun, and insert it into the valve. You can now carefully open the bottom valve and squeeze the cartridge into the system and it will displace the water from the loops as the inhibitor is added. When it’s done, close the bottom valve, remove the inhibitor and put the air valve back in. Open the manifold isolator valves. Let the system run for 10-20 mins to circulate the inhibitor and then top the system pressure up to 2bar. Run again, and bleed the air from the vent. You may need to do this 2 or 3 times, and repressurise to 2bar each time. Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 On 09/01/2021 at 13:39, PeterW said: I’d expect those actuators are spring closed so take one off and see if the flow stops. If not you may have to remove an actuator one at a time. All your circles are spot on ..!! Inhibitor... quickest way is whilst it’s all isolated, close the top and bottom drain valve and then remove the white air vent screw. Get one of these from Screwfix in a standard skeleton gun, and insert it into the valve. You can now carefully open the bottom valve and squeeze the cartridge into the system and it will displace the water from the loops as the inhibitor is added. When it’s done, close the bottom valve, remove the inhibitor and put the air valve back in. Open the manifold isolator valves. Let the system run for 10-20 mins to circulate the inhibitor and then top the system pressure up to 2bar. Run again, and bleed the air from the vent. You may need to do this 2 or 3 times, and repressurise to 2bar each time. Thanks for the reply & guidance @PeterW. I ran through the flushing today on all my zones - wasn't as hard or scary as I first thought! I've also got the inhibitor on hand and will look at putting that in shortly. "Open the manifold isolator valves. Let the system run for 10-20 mins to circulate the inhibitor and then top the system pressure up to 2bar. Run again, and bleed the air from the vent. You may need to do this 2 or 3 times, and repressurise to 2bar each time. " How do I get the system pressure to 2 bar? Is it simply closing off the return valve and keeping the supply valve open? I thought the standard mains supply was only 1 bar, so how would I get it pressurised to greater than the input pressure? After flushing the system is sitting at 0.5 bar, but I've closed the return valve and seeing how high I can get it by keeping the supply open and water flowing. Thanks! Lee Link to comment Share on other sites More sharing options...
JFDIY Posted January 10, 2021 Share Posted January 10, 2021 (edited) There will be a filling loop somewhere, usually near the boiler or whatever your heat source is Typically it'll be a braided Flexi hoses with at least one if not two isolation valves, open theses to allow water into the system Edited January 10, 2021 by JFDIY 1 Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 Cheers - will have a look around. Lee Link to comment Share on other sites More sharing options...
JFDIY Posted January 10, 2021 Share Posted January 10, 2021 Updated my reply above as you were responding 1 Link to comment Share on other sites More sharing options...
PeterW Posted January 10, 2021 Share Posted January 10, 2021 Most likely will be near the boiler - it’s common to the whole system. 1 Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 (edited) I found the filling loop near the expansion tank (not near the boiler in my case), so filled it up to 2bar using the valve (went a little over as per pic of expansion tank & gauge). This is something that I have had to top up every couple of months in the past, as it drops down to around 1 bar or less over that time period. With additional knowledge from undertaking this flushing activity, constantly dropping pressure in this system seems like a "bad thing". I've been doing this for years! So couple of follow up questions: If the boiler pressure is at ~2bar, should the UFH be at the same pressure? The gauge on the UFH manifold indicates otherwise (see pic of gauge att ~0.5bar). What should I do here? Should I be worried about the slow loss of pressure over months from the boiler? Is this an indication of a slow leak somewhere? If so, what can / should I do about this? Regards, Lee Edited January 10, 2021 by PickaxePete clarification Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 Hmmm. I've been thinking about this - I don't think the gauge on the manifold is telling me the pressure of the manifold at all, is it? The manifold will be at the same pressure as the boiler / expansion tank, i.e. approx. 2bar, right? This gauge attached to the manifold is for telling me the pressure of the water only when the return valve is opened (i.e. pressure testing on installation)? If correct, I've answered question (1) myself. Thoughts? Lee Link to comment Share on other sites More sharing options...
JFDIY Posted January 10, 2021 Share Posted January 10, 2021 Is the manifold still isolated at the two ball valves at the end? Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 10 minutes ago, JFDIY said: Is the manifold still isolated at the two ball valves at the end? no - manifold is back in the system. Both valves open. Link to comment Share on other sites More sharing options...
PeterW Posted January 10, 2021 Share Posted January 10, 2021 What’s the boiler pressure ..?? Link to comment Share on other sites More sharing options...
PeterW Posted January 10, 2021 Share Posted January 10, 2021 28 minutes ago, PickaxePete said: no - manifold is back in the system. Both valves open. Errr ... that mixer is back to front if those pipe isolators are correct as hot and cold ..!! If that is correct, it allows hot water to enter the system irrespective if it is needed, and then depending on the flow temperature it lets more back out the colder it gets .... that is the most random manifold I have seen ..!! @Nickfromwales ever seen one of these before ..??! Link to comment Share on other sites More sharing options...
dpmiller Posted January 10, 2021 Share Posted January 10, 2021 cold water has to leave the return to let the manifold loops sup the hot stuff tho? 1 Link to comment Share on other sites More sharing options...
PickaxePete Posted January 10, 2021 Author Share Posted January 10, 2021 12 minutes ago, PeterW said: What’s the boiler pressure ..?? no gauge on the boiler itself but the reading from the expansion tank gauge is about 2 bar. Link to comment Share on other sites More sharing options...
PeterW Posted January 10, 2021 Share Posted January 10, 2021 Ok that’s fine Link to comment Share on other sites More sharing options...
PeterW Posted January 10, 2021 Share Posted January 10, 2021 3 minutes ago, dpmiller said: cold water has to leave the return to let the manifold loops sup the hot stuff tho? Yep but a random way of doing it ..! So if you turn it up, it releases more cold ..? And your blend is wrong as you’re blending the output temperature not the input temperature into the slab so you could in theory be dumping water at 55°C from the boiler straight into the floor with no temperature limitation ... Link to comment Share on other sites More sharing options...
dpmiller Posted January 10, 2021 Share Posted January 10, 2021 there's a capillary coiled up there and i'd presume it's into the flow above the pump Link to comment Share on other sites More sharing options...
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