Plumbing & Plumbers Forum - Rad Sizing - Condensing Combi - Help
Rad Sizing - Condensing Combi - Help
Discuss Rad Sizing - Condensing Combi - Help in the Central Heating Forum at Plumbers Forums; I wonder if someone could advise best practice regarding rad sizing...
House is Victorian semi - 5 beds - 3 reception - 1 bath - 10ft ceilings. Longest run to ...
I wonder if someone could advise best practice regarding rad sizing...
House is Victorian semi - 5 beds - 3 reception - 1 bath - 10ft ceilings. Longest run to rads is 25 metres for the upstairs front bedroom - the boiler is at the rear of the house.
I have just finished calculating the heat loss for each room using Stelrad Stars - the total of which is in the order or 20kw. This was calculated at a minus 5°C outside temperature - this recalculates to around 18Kw at minus 3°C.
The heat loss figures as yet do not include a 10% pipe loss / fast warm up calculation - or a BOE calculation. I'm not sure whether the quoted outputs from Stelrad are for BOE or TBOE etc. Will check with them. I wonder too what flow rate the outputs are based upon and how much that matters?
Boiler is an Intergas 36/30 - radiators will be Stelrad Softline. Boiler will have an external compensating sensor.
The boiler manufacturers data recommends a 20°C supply / return differential if possible - but don't state an ideal return temp. I'm going to assume / aim somewhere below 55°C to achieve better condensing.
So - what should be my next steps?
I can calculate each individual room Delta T as I have the correction table for the rads - which will enable me to more accurately size them.
What flow / return temps should I use? 70/50 - 73/53 - 75/55 - any other combination? I see many installers struggle to get a 20°C differential - what factors affect this? Should i aim for a 15°C differential or less?
Wow. I think you've really put too much effort in to this. But very good for what you have done
If your worried about flow rates
Never run more than 2 rads off a price of 15. And run 22 as far as you can
I think youll be more than fine
"nothing is impossible"
GSR? Want gas safety or boiler repair advice? We will check out that you're genuine via the gas safe website, so please dont be offended when we ask for your details. DIYers, odd job people and have a go heroes need not apply.
Just cube yer room in feet, times by 4, that will give ya BTU's then go 2 rad sizes up. Then go 4 a pint, watch Top Gear, gi your lass a slap an fall asleep on settee wi your kecks round your ankles. That'lle be £200 for the advice. I accept paypal