extension heating system

[chen]

Hello guys, I just done the extension for my 4 bedroom house, the extension includes: new dinning room, new living room, new play room, new guest room, new en-suite bathroom, the builder connected 5 radiators, first he tried to connected our old heating system in garage, our system is 10mm pipe, after connection, new radiators is not hot enough, but bedroom or others are allright. I checked with a corgi friend, he said it is better to connect to the boiler with 22mm pipe, today we tried it, connecting to the kitchen where is boiler there with 22mm, but after that, the new radiator still are not hot enough.

my builder is not good plumber, so I came here, if anyone know any solution for this situation, please let me know. Many thanks. or send email to me on:
[email protected]

 

[REDSAW]

welcome cheng,

check the valves on each side of rads, what are they?.

 

[chen]

already done that, but same.

 

[WHPES]

Your system will probably be out of balance. Google "balancing radiators" and I'm sure you will find a descrtiption of how to do it.

 

[stevetheplumber]

could be that the boiler isnt man enough for the extra rads

 

[dontknowitall]

How are the new radiators connected to the old system?

Hope I'm not teaching you to suck eggs with the following explanation:

(Flow is the hot water from the boiler, return is the cooler water returning to the boiler. Flow is near the top of the boiler, return is near the bottom ... usually!)

Heating systems generally work best with a single main flow and return circuit in 22mm. Although houses are all different, the circuit usually goes up from the boiler and then along the landing and returns back to the boiler again. Where you want radiators you connect one end of the radiator to the flow and the other end to the return, both in either 15mm or 10mm pipe. (Pipes under the floor for upstairs and chased into the walls for downstairs.) But all houses are different and you can find the main circuit and other pipes going all over the place!

The idea is the bulk of the water is cruising around the main ring and when a radiator's TRV calls for heat, some of the heated water diverts off to that radiator. If that radiator is warm enough then the main water flow by-passes that radiator and moves along to the next one. This is called a two pipe system.

Your new radiators might not have been plumbed in a similar fashion. Instead the flow might have been interupted and a new radiator added, then more pipe, then another radiator and so on with the last radiator and pipe being joined to the return. This is a one pipe system. With these systems the first radiator will get the heat and the following ones will receive cooler water. If too many radiators then the last radiator(s) on the system will not receive any hot water at all.

Of course, I might have this totally wrong but then again ...!