Helene Posted January 20 Author Share Posted January 20 13 hours ago, PhilT said: SimonD suggested a 40l/min flow rate, so 33l/min, although very high compared to mine, may not be enough to shove water all the way around your big house and up into your loft K3! Do you have one or two flow pumps? if you have only one either it's not man enough or it is not set to a high enough speed. If you have two, check the other (secondary flow to rads) pump and increase its speed or, if not already, try setting to maximum speed. This should be quite easy as long as you can get access to both. Usually they have 3 speeds which can be adjusted via a dial or a button which selects 1, 2 or 3 lit LED's. You should be able to hear the speed increase. Very interesting - I did change the speed a month or so ago as it was making so much noise - but didn't notice a difference with the rads. I just wish I remembered if the original flow rate was 40 or the same as now, as I've turned the speed back up to maximum last night but the FR didn't increase at all. I'm wondering if the piping is simply not adequate... though the top K3 does work when the other rads are turned off - not sure what it indicates... I'm desperate for the installer to send an engineer but they ignore me... Link to comment Share on other sites More sharing options...
PhilT Posted January 20 Share Posted January 20 51 minutes ago, Helene said: I've turned the speed back up to maximum last night but the FR didn't increase at all. I'm wondering if the piping is simply not adequate... though the top K3 does work when the other rads are turned off - not sure what it indicates... Sounds like you either need stronger pump(s) or the settings need adjusting to allow higher flow rates from the existing pumps. Also someone I know with a similar setup to mine (two pumps) had three pumps installed (one primary, two secondaries) Link to comment Share on other sites More sharing options...
SimonD Posted January 20 Share Posted January 20 20 hours ago, Helene said: The former is hard as it's a big house and I think the circuits splits in various places, and I don't know where... and there are various radiator types... but worth trying again. Even so, they will heat up in some sort of sequence and yes, it might be hard but you have to go through the process if you want to balance your system and get it working properly. 19 hours ago, PhilT said: SimonD suggested a 40l/min flow rate, so 33l/min, although very high compared to mine, may not be enough to shove water all the way around your big house and up into your loft K3! Do you have one or two flow pumps? if you have only one either it's not man enough or it is not set to a high enough speed. If you have two, check the other (secondary flow to rads) pump and increase its speed or, if not already, try setting to maximum speed. This should be quite easy as long as you can get access to both. Usually they have 3 speeds which can be adjusted via a dial or a button which selects 1, 2 or 3 lit LED's. You should be able to hear the speed increase. The circulation of the water in the system isn't just about flow rate, this is some basics on how the system works: Flow rate is determined by the amount of heat you need to move into the house which is in turn determined by your Delta T - the temperature differential between flow and return. The greater the differential, the lower the flow rate, the smaller the differential the higher the flow rate. Once you know your flow rate you then determine the resistance to this flow through the system. The higher the flow rate the higher the resistance becomes in the circuit for the same given pipe diameter. if you double the flow rate you quadruple the resistance and require eight times the power to move the fluid through the system. This is why there is so much talk about needing to upgrade system pipework to accommodate retrofit heat pumps. I think there's an unecessary focus on flow rates right now because the 'low' flow rate could be interpreted in many ways - for example, the circuit has too much resistance for the pump to overcome, or that there is some modulation going on somewhere, or something else. Turning up the pump speed may not have any impact at all on heat distribution, especially if you're dealing with a house with multiple random system extensions - the water could easily be short circuiting back to the heat pump because that's where the lowest resistance is. So some further information is helpful here: what pump do you have? Can you take a photo and post please? However, like it or not, you've simply got to go back to the fundamentals, which means taking a deep breath, taking a good dose of patience and spending the time to balance the radiators. Given that you get heat to the cold rads when you've closed some trvs is a good indicator that you're not actually that far off. So do this and then report back. Link to comment Share on other sites More sharing options...
Helene Posted January 22 Author Share Posted January 22 On 20/01/2024 at 13:50, SimonD said: Even so, they will heat up in some sort of sequence and yes, it might be hard but you have to go through the process if you want to balance your system and get it working properly. The circulation of the water in the system isn't just about flow rate, this is some basics on how the system works: Flow rate is determined by the amount of heat you need to move into the house which is in turn determined by your Delta T - the temperature differential between flow and return. The greater the differential, the lower the flow rate, the smaller the differential the higher the flow rate. Once you know your flow rate you then determine the resistance to this flow through the system. The higher the flow rate the higher the resistance becomes in the circuit for the same given pipe diameter. if you double the flow rate you quadruple the resistance and require eight times the power to move the fluid through the system. This is why there is so much talk about needing to upgrade system pipework to accommodate retrofit heat pumps. I think there's an unecessary focus on flow rates right now because the 'low' flow rate could be interpreted in many ways - for example, the circuit has too much resistance for the pump to overcome, or that there is some modulation going on somewhere, or something else. Turning up the pump speed may not have any impact at all on heat distribution, especially if you're dealing with a house with multiple random system extensions - the water could easily be short circuiting back to the heat pump because that's where the lowest resistance is. I tried to change the speed and the flow rate didn't increase indeed. The top floor K3 badly needed bleeding actually (again) - so I was hopeful it was going to sort everything but I still have the same issue. On 20/01/2024 at 13:50, SimonD said: So some further information is helpful here: what pump do you have? Can you take a photo and post please? I need to take a picture of the pump, it's a Mitsubishi Zubadan 14Kw. Here is a picture of the system, not sure what these things are called Hopefully it's good enough. I'm puzzled about why one red pump is upside down - I'm sure there's a reason. But they don't seem to be at their maximum, at least one of them. On 20/01/2024 at 13:50, SimonD said: However, like it or not, you've simply got to go back to the fundamentals, which means taking a deep breath, taking a good dose of patience and spending the time to balance the radiators. Given that you get heat to the cold rads when you've closed some trvs is a good indicator that you're not actually that far off. So do this and then report back. It's definitely something I want to nail indeed. thank you Link to comment Share on other sites More sharing options...
SimonD Posted January 22 Share Posted January 22 4 hours ago, Helene said: I tried to change the speed and the flow rate didn't increase indeed. The top floor K3 badly needed bleeding actually (again) - so I was hopeful it was going to sort everything but I still have the same issue. I need to take a picture of the pump, it's a Mitsubishi Zubadan 14Kw. Here is a picture of the system, not sure what these things are called Hopefully it's good enough. I'm puzzled about why one red pump is upside down - I'm sure there's a reason. But they don't seem to be at their maximum, at least one of them. It's definitely something I want to nail indeed. thank you Okay, so the plot thickens. You've got 2 commercial circulating pumps installed on your system - these are your red things. Both are set to number 3 as shown by the lights. We definitely need to understand how these have been plumbed in as it seems quite incredible that your system with just 18 rads needs two of them running at setting 3. And you're right about them being installed different ways not looking right, but as always it depends on the plumbing. Are you able to take photos to show the whole area of pipework so we can see more? If the heating system is producing lots of air, it can sometimes be a sign that the pumps are churning rather than pumping. Link to comment Share on other sites More sharing options...
TonyT Posted January 22 Share Posted January 22 Air lock Keep topping up and bleeding the rads.. Link to comment Share on other sites More sharing options...
Helene Posted January 22 Author Share Posted January 22 12 minutes ago, SimonD said: Okay, so the plot thickens. You've got 2 commercial circulating pumps installed on your system - these are your red things. Both are set to number 3 as shown by the lights. We definitely need to understand how these have been plumbed in as it seems quite incredible that your system with just 18 rads needs two of them running at setting 3. And you're right about them being installed different ways not looking right, but as always it depends on the plumbing. Are you able to take photos to show the whole area of pipework so we can see more? If the heating system is producing lots of air, it can sometimes be a sign that the pumps are churning rather than pumping. I hope a few of these pictures help, it's really hard to take a picture as there are pipes in the way. So you think potentially two pumps is over the top? In this case I would think my whole system would be flying but instead it seems feeble. Link to comment Share on other sites More sharing options...
Helene Posted January 22 Author Share Posted January 22 8 minutes ago, TonyT said: Air lock Keep topping up and bleeding the rads.. I'm unsure it's the case as there was no air for a while when I last bled them, it might be because I've balanced the rads again, changed speed pump, etc. Link to comment Share on other sites More sharing options...
SimonD Posted January 22 Share Posted January 22 19 minutes ago, Helene said: I hope a few of these pictures help, it's really hard to take a picture as there are pipes in the way. So you think potentially two pumps is over the top? Unfortunately those aren't really going to help. We've got to determine where the pipes come from and where they lead to. We also need to understand how the pumps have been installed - are they in parallel or in series and is there some kind of hydraulic separation installed too? Unless there's a piece of equipment, like the heat pump heat exchanger that has a very high flow resistance, I think that 2 of these pumps is over the top, eve a single one of these in most houses is over the top. But, there may be a reason. What has happened to the installers? Are they not available to answer questions and help with getting this sorted as to me it points to a basic customer service issue. I certainly wouldn't leave a customer of mine with a system that didn't work properly. Link to comment Share on other sites More sharing options...
Helene Posted January 22 Author Share Posted January 22 5 minutes ago, SimonD said: Unfortunately those aren't really going to help. We've got to determine where the pipes come from and where they lead to. We also need to understand how the pumps have been installed - are they in parallel or in series and is there some kind of hydraulic separation installed too? Unless there's a piece of equipment, like the heat pump heat exchanger that has a very high flow resistance, I think that 2 of these pumps is over the top, eve a single one of these in most houses is over the top. But, there may be a reason. I will try to look more closely at the piping, but hard when I'm not used to any of it. maybe a video could help? 5 minutes ago, SimonD said: What has happened to the installers? Are they not available to answer questions and help with getting this sorted as to me it points to a basic customer service issue. I certainly wouldn't leave a customer of mine with a system that didn't work properly. Very good question - they were supposed to send an engineer two months ago, now it's radio silence - needless to say that I am appalled. I've just sent yet another email to inform them that I'm going to charge them for an engineer visit that I will arrange myself. Link to comment Share on other sites More sharing options...
Helene Posted January 22 Author Share Posted January 22 33 minutes ago, SimonD said: Unfortunately those aren't really going to help. We've got to determine where the pipes come from and where they lead to. We also need to understand how the pumps have been installed - are they in parallel or in series and is there some kind of hydraulic separation installed too? Unless there's a piece of equipment, like the heat pump heat exchanger that has a very high flow resistance, I think that 2 of these pumps is over the top, eve a single one of these in most houses is over the top. But, there may be a reason. Here is video https://photos.app.goo.gl/8XUp77f5hGCiCPoj8 Hope it helps a bit more. Thanks Link to comment Share on other sites More sharing options...
sharpener Posted January 22 Share Posted January 22 The brass thing to the right of the pressure gauge is an automatic air vent, unscrew the small screw on top a couple of turns so the trapped air can be released. Link to comment Share on other sites More sharing options...
ReedRichards Posted January 22 Share Posted January 22 I've always been a bit puzzled by those air vents. If they are "automatic", why do you need intervene manually and loosen the screw? Link to comment Share on other sites More sharing options...
dpmiller Posted January 23 Share Posted January 23 5 hours ago, ReedRichards said: I've always been a bit puzzled by those air vents. If they are "automatic", why do you need intervene manually and loosen the screw? coz they fail often and drip gently. When working fine, you'll get a small volume of trapped air- at system pressure- above the internal float that'll hiss impressively when you slacken the schrader cap. Link to comment Share on other sites More sharing options...
TonyT Posted January 23 Share Posted January 23 What kind of hot water cylinder is that? is it unvented? Link to comment Share on other sites More sharing options...
PhilT Posted January 23 Share Posted January 23 10 hours ago, SimonD said: I think that 2 of these pumps is over the top, eve a single one of these in most houses is over the top How would you get any circulation without at least one pump? Link to comment Share on other sites More sharing options...
sharpener Posted January 23 Share Posted January 23 (edited) Most HPs have a powerful circulating pump in the outdoor unit. You only need an additional pump if you have got a buffer tank or low loss header so there is hydraulic separation if you have a mixing valve on the UFH if you have a large radiator system - in which case balancing the work rate of the two pumps is not easy if you have a secondary circulation loop on the DHW Edited January 23 by sharpener Link to comment Share on other sites More sharing options...
SimonD Posted January 23 Share Posted January 23 21 minutes ago, PhilT said: How would you get any circulation without at least one pump? In most domestic properties, you don't need a commercial circulating pump capable of that kind of head and flow volume, so you choose a pump more suitable, like a domestic circulating pump - for example: Grundfos UPS3 or a Wilo Pico, each of which also have proportional pressure Link to comment Share on other sites More sharing options...
SimonD Posted January 23 Share Posted January 23 2 hours ago, TonyT said: What kind of hot water cylinder is that? is it unvented? It is unvented. Link to comment Share on other sites More sharing options...
sharpener Posted January 23 Share Posted January 23 (edited) 2 hours ago, TonyT said: What kind of hot water cylinder is that? is it unvented? Looks like it, there are two expansion vessels, one is connected directly to the top tapping on the cylinder Edited January 23 by sharpener Link to comment Share on other sites More sharing options...
SimonD Posted January 23 Share Posted January 23 10 hours ago, Helene said: Here is video https://photos.app.goo.gl/8XUp77f5hGCiCPoj8 Hope it helps a bit more. Thanks Yes, that's more helpful. From the looks of it you have one pump on the flow side - this pumps your hot water into the heating system and hot water cylinder - and one pump on the return side - pumping the cooler heating water back to the heat pump. The flow appears to be on the left, the return on the right, just after the system filter (the black bubble thing). I'm not familiar with the Mitsubishi Zubadan and can't find any tech specs indicating a need to install two pumps in series, nor can I find the heat ex resistance values other than that the pipework needs to be designed for flows that can exceed 1.5m/s. It's not unheard of for this to be recommended in some circumstance, or when one pump sits before a buffer and another after a buffer, but the question still remains as to why on your system? And then we've got the question as to why you're not getting sufficient flow rates even with the two pumps. I would be calling up Mitsubishi technical department to ask questions about the installation recommendations to determine the need to 2 pumps but it does seem like you need to get someone in to take a closer look at the installation. 11 hours ago, Helene said: Very good question - they were supposed to send an engineer two months ago, now it's radio silence - needless to say that I am appalled. I've just sent yet another email to inform them that I'm going to charge them for an engineer visit that I will arrange myself. Was the installer MCS certified? And do you know which Certification body they're a member of (e.g. NICEIC, OFTEC etc.). It is possible to raise a complaint through these organisations for FWIW, but at least if it starts costing you money getting someone else in, you've got a better case to claim back the costs. If you complain through these bodies, the installer does at least have a time limit to act. Because you did manage to get heat to your cold radiators when you closed some trvs, I still think it's worth trying to balance the radiators while you're trying to sort this all out. It's also worth getting yourself set up with melcloud so you can see the functioning of the heat pump and energy use. 1 Link to comment Share on other sites More sharing options...
TonyT Posted January 23 Share Posted January 23 2 hours ago, SimonD said: It is unvented. Didn’t see a tundish? Link to comment Share on other sites More sharing options...
sharpener Posted January 23 Share Posted January 23 28 minutes ago, TonyT said: Didn’t see a tundish? No but the temp/pressure relief valve is clearly visible in the vid at 0'20" and there is something teed into the outlet just after it so maybe combined with heating system pressure relief (though I can't see that tbh). Full marks to @SimonD for figuring out the pipe runs. Link to comment Share on other sites More sharing options...
TonyT Posted January 23 Share Posted January 23 Video zoomed out a bit would be helpful to see other pipework. Link to comment Share on other sites More sharing options...
SimonD Posted January 23 Share Posted January 23 2 hours ago, TonyT said: Didn’t see a tundish? It's in the photo Link to comment Share on other sites More sharing options...
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