Russdl Posted January 27, 2022 Share Posted January 27, 2022 Our Willis heater based UFH doesn't seem to be working as advertised. The problem as far as I can see it is that the flow rates through the various UFH loops are nowhere near high enough and I can't get them any higher. We have a total of 11 loops and as I understand it the flow rate through the various UFH pipe loops should be 0.5 litre/min per 20m pipe, so for example one of our pipe runs is 90m long so it should have a flow rate of 2.25 litres/min. First question, is the above correct? Link to comment Share on other sites More sharing options...
markc Posted January 27, 2022 Share Posted January 27, 2022 2 minutes ago, Russdl said: Our Willis heater based UFH doesn't seem to be working as advertised. The problem as far as I can see it is that the flow rates through the various UFH loops are nowhere near high enough and I can't get them any higher. We have a total of 11 loops and as I understand it the flow rate through the various UFH pipe loops should be 0.5 litre/min per 20m pipe, so for example one of our pipe runs is 90m long so it should have a flow rate of 2.25 litres/min. First question, is the above correct? I’m no UFH expert but looking at this from an Hydraulic viewpoint, 11 loops regardless of length will require a high volume pump to provide a descent flow rate through them all at the same time. So I would say this is a pump capacity issue Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 4 minutes ago, markc said: So I would say this is a pump capacity issue I'm assuming the same, but I thought I'd better start with the basics and check what flow rates i should be aiming for in the first place. Link to comment Share on other sites More sharing options...
Radian Posted January 27, 2022 Share Posted January 27, 2022 Loop length divided by 40 is what I've seen as a recommended flow rate, which is 2.25l/m as you say. The head loss in that 90m run equates to around 1.4m (according to this calc.) but that doesn't account for manifolds, blending valves etc. If this loop is representative of the other then it's looking like the circulator is limiting you. Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 @Radian thanks for confirming that. Ive got 11 loops. The longest being 98m which requires 2.5l/min flow, the shortest 28m so 0.75i/min. With all the loops open fully I get barely a reading on any of the flow gauges. If I close them all except 1 loop I can get up to 2.5l/min on the only open loop but the rate quickly reduces if I open up another loop. I think the pumps are set up correctly but what is the correct sequence for setting up the flow rates? If it's just 'turn it on and adjust the flow rates' then I'm stuffed. If there's more to it than that what is the correct sequence? Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 The black Grundfos pump is set to ‘Constant Pressure 3’ which is the highest it can be set to. However the displayed 1 green and 2 yellow LED’s in the picture show that it is on ‘medium low performance’. I have no idea how to get it to 1 green and 4 yellow LED’s (high performance) which may be all I need to do? Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 The blue Salus pump was set to ‘Auto’ but its now set to ‘HD2’ which is the highest constant pressure curve. Link to comment Share on other sites More sharing options...
Radian Posted January 27, 2022 Share Posted January 27, 2022 51 minutes ago, Russdl said: The black Grundfos pump is set to ‘Constant Pressure 3’ which is the highest it can be set to. However the displayed 1 green and 2 yellow LED’s in the picture show that it is on ‘medium low performance’. I have no idea how to get it to 1 green and 4 yellow LED’s (high performance) which may be all I need to do? OMG, I've got exactly the same same pump and exactly the same question! It hasn't shown up as a problem for me (only one 100m loop) so I've never looked into it further but agree, it's rather puzzling. Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 @Radian I’m sat here looking at it whilst it’s running and the third yellow LED is occasionally lighting up so I guess it increases the performance automatically (I certainly can’t find any way of changing it manually). I’m sure it’ll do 100m with ease but something is not quite right somewhere in my 823m. Link to comment Share on other sites More sharing options...
joe90 Posted January 27, 2022 Share Posted January 27, 2022 After my re plumbed buffer tank episode I am struggling to get my flow rates to 2 with only 5 near 100m loops and the pump set to max (6) ?♂️ Tho at least I get a decent temp (30’) now. I did ask this question elsewhere but didn’t see a reply, without a flow gauge what is the optimum flow rate through the actual ASHP to get the best results from it?. Link to comment Share on other sites More sharing options...
SteamyTea Posted January 27, 2022 Share Posted January 27, 2022 32 minutes ago, joe90 said: what is the optimum flow rate through the actual ASHP to get the best results from it Whatever flow rate gives you the optimal temperature difference between flow and return. Does the ASHP state that temperature difference? 1 Link to comment Share on other sites More sharing options...
Russdl Posted January 27, 2022 Author Share Posted January 27, 2022 With all 11 loops open my flow rates are way below 1 litres/min and I'm trying to get 2.25 to 2.5 litres/min on 5 of the loops. Is it that our pump isn't up to the job or has the pump not been set up correctly? Or is there something else going on? Link to comment Share on other sites More sharing options...
dpmiller Posted January 27, 2022 Share Posted January 27, 2022 The ASHP will have a minimum flow requirement We've about 650m over 12 loops of very unequal lengths- from around 30 to 90m. But I've no problem getting heat to all the rooms with a Yonos Pico 25 1/6 running at under 2m. There's about 1.5l/s on the loops with the highest demand Link to comment Share on other sites More sharing options...
PeterW Posted January 27, 2022 Share Posted January 27, 2022 12 hours ago, Russdl said: First question, is the above correct? No, as it doesn’t take into consideration the flow through the heat source. You need the design flows. 10 hours ago, Russdl said: The blue Salus pump was set to ‘Auto’ but its now set to ‘HD2’ which is the highest constant pressure curve. What does the blue pump go to ..? What circuit ..? 9 hours ago, Russdl said: I’m sure it’ll do 100m with ease but something is not quite right somewhere in my 823m. UPM3 will do 12 circuits and over 1,000m of pipe with ease - have you changed anything else ..? Link to comment Share on other sites More sharing options...
Russdl Posted January 28, 2022 Author Share Posted January 28, 2022 3 hours ago, PeterW said: it doesn’t take into consideration the flow through the heat source. You need the design flows. i don’t have those design flows or any idea how to calculate them. Is there a rule of thumb? 3 hours ago, PeterW said: What does the blue pump go to ..? What circuit ..? A short distance above the blue Salus pump are the twin Willis heaters. The blue pump is the return from the manifolds into the bottom of the Willis heaters. The black Grundfos pump is between the supply and return manifolds of the UFH as you can probably see from the picture. 3 hours ago, PeterW said: have you changed anything else No, and I’ve put the Salus pump back into ‘Auto’ as the ‘HD2’ setting made not a jot of difference. 3 hours ago, PeterW said: UPM3 will do 12 circuits and over 1,000m of pipe with ease Any idea why it’s doesn’t seem to be handling it in my setup? My two shorter runs which by my (probably incorrect) calculation require 0.75l/min are set to about that. The other 9 loops which require 1.75l/min and more are fully open and barely registering 0.5l/min. Link to comment Share on other sites More sharing options...
dpmiller Posted January 28, 2022 Share Posted January 28, 2022 (edited) what are the two bypass controls set to? and is the hidden isolator fully open? Edited January 28, 2022 by dpmiller Link to comment Share on other sites More sharing options...
ProDave Posted January 28, 2022 Share Posted January 28, 2022 I don't see loop length has any bearing on flow rate. Flow rate is determined by the heat output you need. e.g it does not matter of a room has 1 loop of 100 metres or 2 loops of 50 metres, each loop will still need the same flow rate to achieve the same heat output Link to comment Share on other sites More sharing options...
Russdl Posted January 28, 2022 Author Share Posted January 28, 2022 @dpmiller thanks for that link, I didn't't see that post when I was searching. I'll check... @ProDave The problem is, I can't achieve any flow rate of any significance. Link to comment Share on other sites More sharing options...
Russdl Posted January 28, 2022 Author Share Posted January 28, 2022 ??? Link to comment Share on other sites More sharing options...
dpmiller Posted January 28, 2022 Share Posted January 28, 2022 6 minutes ago, Russdl said: ??? and??? Link to comment Share on other sites More sharing options...
joe90 Posted January 28, 2022 Share Posted January 28, 2022 Do the Willis heaters have any restrictions? (Don’t know anything about them, just putting it out there?♂️) Link to comment Share on other sites More sharing options...
Russdl Posted January 28, 2022 Author Share Posted January 28, 2022 (edited) @dpmiller thanks again for posting the link to that Iver thread. @andy top, top tip. My quarter turn isolation valve was closed. Its now open and the flow rates are epic! In the words of the plumber that installed ours... "...Not checking pump / gate valves are open is 1st year apprentice error. I’ve not had one yet which has caused any issues." Feel free to put ours down as No1 if you wish. ? Edited January 28, 2022 by Russdl Though I'd just highlight what my issue was :-) 1 1 Link to comment Share on other sites More sharing options...
dpmiller Posted January 28, 2022 Share Posted January 28, 2022 Bwahahaha! Priceless!!!! Link to comment Share on other sites More sharing options...
SteamyTea Posted January 28, 2022 Share Posted January 28, 2022 7 minutes ago, Russdl said: quarter turn isolation valve was closed. Its now open and the flow rates are epic Your heating bill will go up now. Link to comment Share on other sites More sharing options...
Russdl Posted January 28, 2022 Author Share Posted January 28, 2022 6 minutes ago, SteamyTea said: Your heating bill will go up now ?? Indeed, as we now have a functioning heating system it undoubtedly will. ??? (Sorry, I just can't stop laughing ?) Link to comment Share on other sites More sharing options...
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