Originally the installer planned to set the system up for 50c but I asked for 45c as I'd understood this would be more efficient. I didn't mind if that meant bigger radiators. After the install I tinkered the weather comp down to 43c (for the lowest outdoor temp). 42 wasn't warm enough.
Originally the installer planned to set the system up for 50c but I asked for 45c as I'd understood this would be more efficient. I didn't mind if that meant bigger radiators. After the install I tinkered the weather comp down to 43c (for the lowest outdoor temp). 42 wasn't warm enough.
The heat loss for the bathroom should have been calculated for an IAT of 22C. Without seeing an actual heat loss calculation sheet detailing wall, roof and floor size and type, along with windows size and type, I cannot confirm if the figures provided are correct or not.
Assuming that they are, to meet a heat loss of 7.6kW would require a LWT of approximately 50C.
Adjusting the WC curve normally involves setting the warm weather end at something like a LWT of 25C at an OAT of 20C, with the cold weather end being a LWT of 50C at an OAT of -5C. Then observe how the system responds under varying weather conditions and gradually adjust the cold weather end to achieve the desired IAT. Obviously the radiators need to be balanced to achieve individual room temperature requirements.
I did adjust the ABV, firstly to 0.5 then 0.6. I noticed the flow rate drop, not sure if this was coincidental but the Samsung controller went as low 11.5 lpm. I don't if the ABV change caused this or whether it was coincidental. I thought it would error below 12 lpm, so this surprised me. Is it possible to bypass the shut down in settings? Maybe my installer did that, I wouldn't put it past them.
My system was supposed to be configured for 45c but again, I have no faith in them at all.
Sadly, the only space I can see on the system for this is further down the same pipe before the TF1. This is a vertical pipe with a downward flow, which I know isn't ideal.
Maybe my installer did that, I wouldn't put it past them.
My system was supposed to be configured for 45c but again, I have no faith in them at all.
I strongly suspect that we have the same installers. Does G L ring a bell? I think you were fortunate to escape from having the buffer tank fitted, as you now have a direct system, which is generally thought to be most efficient. I believe that your system was running pretty well last winter from the posts you made last year, so I would hope that it would continue to do so, despite some theoretical problems discussed above. By the way, your piping diagrams were very impressive. What software did you use?
I strongly suspect that we have the same installers. Does G L ring a bell?
Yes. What a nightmare.
I think you were fortunate to escape from having the buffer tank fitted, as you now have a direct system, which is generally thought to be most efficient. I believe that your system was running pretty well last winter from the posts you made last year, so I would hope that it would continue to do so, despite some theoretical problems discussed above. By the way, your piping diagrams were very impressive. What software did you use?
Thanks, I just used the online editor at https://app.diagrams.net/ which is free to use. The only drawback is having to download the file each time you save but that is a minor annoyance.
Thank you for all your time and effort, it's very much appreciated.
This post was modified 7 months ago 4 times by RiponOwl
. I think that you should be multiplying 17kW by 0.46, which would give you an answer of 7.82kW at an IAT of 20C
Thanks Derek. That clarifies a lot. It has been very useful to work out the DT ratings of radiators when operating at the lower flow temperatures of a heat pump.
EG the 17kw rating of @riponowl s installation only actually has a capacity of 7.82kwh when operating at a Flow temperature (LWT) of 50c. And at the lower modulation when operating such as at a flow temperature of 35c the output capacity of these radiators drops to 2.8kwh. To my mind this would almost certainly be below the minimum operating output of a larger heat pump.
Derek, Apologies if this is a nonsense question but-Can you confirm :- does this mean the lower modulating heat range of a heat pump would not be reached due to the radiators not having the heat dumping capacity? Is this what might cause rapid cycling? Or does something else happen to allow a heat pump compressor to operate at a lower flow temperature?
