Alot of them are done at 75-65 20rt to give the dt50, the dt10 on a radiator works well and what iv started designing of especially with wc or low temp gas👍
Very clear and useful video. Explained very well. Quick question, does it matter what size the pipework is to the radiator from the 22mm flow and return. I was told by a registered iphe, that from 22mm flow and return. One should use no more than 3metres of 10mm mircobore or 15mm piping. As this affects the flow and return temperatures. Your opinion would be greatly appreciated please. Thank you
I always use twin finned when I do a system, with the condensers to increase surface area. Then run my flows at 62. But I need to get more technical haha
Maybe a slightly stupid question; when looking to do low temp, once I've established the kW of the radiators (roughly 3 times what the catalogue lists at dt50), do I then use those increased values, adding them up from all the radiators - to size the boiler for the whole house, or do I go with the result of my heat loss calculation to find a suitable boiler?
With a Viessmann 200 boiler sizing is easy. It modulates down to 1.9 for heating and up to 32kw for hot water. I use the old whole house method to check for boiler size. Don't try adding radiators as this is a big waste of time imo.
Great video, is there a way of estimating pre existing radiators power, and can you simply add extra ones to increase the total output into the room? I have old cast iron ones and have been wanting to supliment them but as the property is old, i would really like to get the most out of my condensing boiler.
I think so. A heatloss calculation to establish the heat requirement first. Next look for some source of information on the published output if your existing radiators or similar. This is a good starting point. Need to calculate f factors for adjusting output and then select replacement or additional radiators.
Thanks Andrew Based on your video as a rule of thumb then we need to triple the size of rads when we calculate at the brochure outputs of delta t 50 for a delta t 20. I love rule of thumb when quoting for quick quoting purposes. I may not get the job and prefer not to spend to long on paperwork. Will this methodology work for quick quoting in your opinion.😃😇
The former Andrew. Not disagreeing. I know its 0.4 to the power of 1.24, but can't see how you get to .321 - ie what buttons on the calculator you push - or how you do it longhand. Thanks
Thank you for this, exactly what I needed to know/understand
Alot of them are done at 75-65 20rt to give the dt50, the dt10 on a radiator works well and what iv started designing of especially with wc or low temp gas👍
Wht dt 10 on the rad ?
@@andrewmillwardwatford9410 yeah, that is with a lower temp wc system, dt10 is more realistic on those systems I find 👍
@@stevencalvert9454 need to look at this idea on the forum
Explained really clearly, thanks !
Outstanding!
Great explanation.
Very clear and useful video. Explained very well. Quick question, does it matter what size the pipework is to the radiator from the 22mm flow and return. I was told by a registered iphe, that from 22mm flow and return. One should use no more than 3metres of 10mm mircobore or 15mm piping. As this affects the flow and return temperatures. Your opinion would be greatly appreciated please. Thank you
No it's wrong
@@andrewmillwardwatford9410 so would not the size of flow and return pipes not affect the output (btu) of the radiator then?
I always use twin finned when I do a system, with the condensers to increase surface area. Then run my flows at 62. But I need to get more technical haha
Maybe a slightly stupid question; when looking to do low temp, once I've established the kW of the radiators (roughly 3 times what the catalogue lists at dt50), do I then use those increased values, adding them up from all the radiators - to size the boiler for the whole house, or do I go with the result of my heat loss calculation to find a suitable boiler?
With a Viessmann 200 boiler sizing is easy. It modulates down to 1.9 for heating and up to 32kw for hot water. I use the old whole house method to check for boiler size. Don't try adding radiators as this is a big waste of time imo.
This is great, Thanks !
Great video, is there a way of estimating pre existing radiators power, and can you simply add extra ones to increase the total output into the room? I have old cast iron ones and have been wanting to supliment them but as the property is old, i would really like to get the most out of my condensing boiler.
I think so. A heatloss calculation to establish the heat requirement first. Next look for some source of information on the published output if your existing radiators or similar. This is a good starting point. Need to calculate f factors for adjusting output and then select replacement or additional radiators.
So should I need to do more correction factors, I simply add them together? Before dividing them by my Watts required
I believe the other factors are now dismissed from the book.
Thanks Andrew
Based on your video as a rule of thumb then we need to triple the size of rads when we calculate at the brochure outputs of delta t 50 for a delta t 20. I love rule of thumb when quoting for quick quoting purposes. I may not get the job and prefer not to spend to long on paperwork. Will this methodology work for quick quoting in your opinion.😃😇
Yes. It's not vital to be that accurate in the quote or in practice. Rule of thumb is great if up to date.
Hi. Great vid. Thanks. My maths is a bit dodgy. How do you get 0.321 from 0.4 to the power of 1.24?
Do you mean how did I calculate it or are you disagreeing with my answer ?b
The former Andrew. Not disagreeing. I know its 0.4 to the power of 1.24, but can't see how you get to .321 - ie what buttons on the calculator you push - or how you do it longhand. Thanks
@@davebaber5371 it's not easy. I can't post a screen shot here. Feel free to pm me for the answer
Good stuff - thank you.👍
Where i can find the the domestic heating design guide
Cibse sell it
How much is the condensing side of things worth in efficiency and is it really worth upsizing all rads to get the boiler condensing more.
I have no idea of the extra efficiency tbo. But most existing radiators run at 55 35 without any up sizing anyway.
If you size the rads for 55/35, on WC, you'll get an extra 10-15%.
Which heat loss calculator do you use to get initial heat demand?
Try heat-engineer it’s basically that book turned into software. Have to pay for it though.
Agree. Heating engineer software