Discuss What size boiler needed in the Central Heating Forum area at PlumbersForums.net
Yes expansion valve on HW cylinder was dripping, with that bypass valve open hot water was feeding down the pipe to where the EV is on cylinder. Nothing else was calling for heat other than Kitchen UFH with manual bypass open. Boiler pressure was 1.5 bar, pump was 1.35 bar, flow temp was 72 degrees. (Hope that makes sense)Do you mean the expansion valve on the HW cylinder is dripping, if so, this, or a failing HW cylinder EV has got nothing to do with the boiler EV or PRV, what is/was the boiler pressure gauge reading when this dripping occurs?.
Ok so you get a burner output and a boiler output from one nozzle calculations?If that bypass valve is feeding HOT water into the HW cylinder then it will have to be from the HW cylinder hw outlet which will be at higher pressure when the cylinder is heating or is hot with no HW draw off, if tied into the boiler system primary system flow pipe it cannot feed hw as the primary/boiler system pressure is only 1.5bar. If it was connected from the cold mains then that will lift the cylinder expansion valve but the pipe would be cold.?
Nozzle Sizing: From below. a 0.65 nozzle will give a burner output of 31kw @ 12.5bar which will be 31*(14/12.5)^2, 32.81kw @ 14bar, a boiler output of 28.87kw @ 88% boiler efficiency.
Your present 0.55?? nozzle will give a burner output of 26kw @ 12.0bar which will be 26*(14/12.0)^2, 28.10kw @ 14bar, a boiler output of 24.73kw @ 88% boiler efficiency.
Thank you for the calculations they are very handy.Yes, the table gives (presumably) burner output, the only assumption that will marginally affect the boiler output is its efficiency so 85% to 92% should cover it, the calculation for pressure is universally used, ie flow is prop to the sq.root of pressure, I should have shown that as ^0.5 and not ^2, but I did use ^0.5 in the calculation.
Can't really comment on that by pass except to suggest finding out exactly where the connections are teed in.
Ok, will do. I’ll get back to you.This Laundry Manifold/TMV is a mystery to me as all the indications are that the return temperature to the boiler is the mixed flow temperature but havn't figured out if this is thermodynamically possible.
You might please take the (4) temperatures where indicated and also take the return temperature to the boiler; at the boiler.
View attachment 76807
Boiler set point 60This Laundry Manifold/TMV is a mystery to me as all the indications are that the return temperature to the boiler is the mixed flow temperature but havn't figured out if this is thermodynamically possible.
You might please take the (4) temperatures where indicated and also take the return temperature to the boiler; at the boiler.
View attachment 76807
Oh sorry, I’ll check againSorry for confusing you, its the temperatures at 1,2,3&4 in this attachment I would like.
Oh sorry,Sorry for confusing you, its the temperatures at 1,2,3&4 in this attachment I would like.
Awesome, sorry have been away for back tomorrow and then I’ll have temps. Thank you.Have added another one below, point 5, so measurements at points 1,2,3,4,5. (thanks for your patience)
Ok so I have checked all temperatures and what a shambles, they areOh sorry,
Awesome, sorry have been away for back tomorrow and then I’ll have temps. Thank you.
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