Central Heating Question

[Leoki]

Default Central Heating Pipework



Hi All

If you have the time could you have a think about the following for me please, any advice would be gratefully received.

I am doing some work for a customer early in the new year, Im replacing 3 x existing wall hung steel panel radiators with newer compact radiators.

The loft in the property has been converted and I have been asked to put two compact radiators upstairs as well. It’s a large old Victorian style building so it’s a really nice loft space with windows at each end. One new radiator to go under each window. Distance between the front and back walls/windows is about 11 metres.

On the first floor there is the main family bathroom and 3 x bedrooms. The bathroom and one bedroom are at the back end of the house, each with an existing radiator in it, a bedroom in the middle of the first floor, the third bedroom being at the front of the house again with an existing radiator fitted.

I want to keep the length of pipe runs to a minimum, Im therefore thinking of coming off the flow and return (two pipe system) from existing radiators on the first floor in the front and back bedrooms, exposed pipework neatly running up the wall through the ceiling coming up into the loft directly above, under the window where the new radiators will be situated.

The house is served by a relatively new Worcester Bosch Greenstar Junior 28i combi boiler.

Any thoughts on this, any other observations. Cleaning of soldered pipework and inhibiting of the central heating system are already a given.

The system presently has 12 x radiators of various sizes connected, three proposed new ones would take that to 15 in total. The boiler has an maximum output of 28kw on the heating side. I will try and get some information from WorcesterBosch as to pump head values.

Thankyou

 

[IDCHAPPY]

Unless the radiators are huge you shouldn't have a problem with the heating load.
I presume it's 15mm you are coming off and up to the loft with?
Cheers Ian

 

[chris watkins]

Taking it that the system is designed & set up to run at 20deg C between the flow & return then as an approximate guide 15mm will carry a max of 11kWs & 22mm 23kW but if as you say old stuff on the system they will have been sized for 11deg C in which case it will only be 6 & 13kW.

Try to find out what size pipes feed the upper floors were you want to add rad's, total up the outputs from the existing rads connected to this and add the outputs from the new you are proposing. So long as the total does not exceed the totals I have listed above you should be OK.

Two things
1. Watch the exposed pipework as this will loose heat in the rooms you don't want & effect what is available above.
2. Recommend you invest in a very good book called the "Domestic Heating Design Guide" 2013 its the dogs do-dars.

 

[doitmyself]

Taking it that the system is designed & set up to run at 20deg C between the flow & return then as an approximate guide 15mm will carry a max of 11kWs & 22mm 23kW but if as you say old stuff on the system they will have been sized for 11deg C in which case it will only be 6 & 13kW.

The mfr quotes 2m available head for a 20C differential. If the system has been balanced for a 10/11C drop, the available head will be much less.

As most older systems will, in all probability, have been over-spec'd, a reduction in rad output of about 15%, when run at 75/55, will not be noticed.