Inline pump

[Henchman76]

Hello everyone hope your all doing well. I am pricing up a job for which the client has requested an inline pump to be fitted to the back half of a scheme due to poor circulation on a 17 radiator heating system which is in part down to the incorrect bore of pipework feeding the back half of the scheme and a 28KW boiler which services this circuit. I was just going to put a 15/60 grunfos pump on to the return/flow just before the circuit extends to these problem radiators but I was wondering how to best wire it in. Do I just run the cable back to boiler and wire the live from the pump into the LR from the R/Stat ?

The system I am told has been flushed previously, its also has a magnaclean fitted on the return. I am also lead to believe that the system has been balanced numerous times by BG but this only cures the problem for a short while until the flow issue rears its head once again. The pipework is exposed at high level which will also be contributing to heat loss aswell as the inadequate pipework (15mm) and subsequent drops.

Hs anyone any extra ideas on how to tackle this problem and of course how to best wire in the 15/60 ? Thankyou for taking time to answer

 

[kimbo]

Rather than spend any more money on trying to get it to work, after all if the pipework is the wrong size it probably wont work, best bite the bullet and change the pipework, I have just done one recently and they have had everything done that you are about to do and it still doesnt work, I correctly sized the pipes and no more problems. 15mm pipe can only carry a certain amount of BTU,s I cant remember how much, but you cant get a quart out of a pint pot as they say.

 

[Pssst]

The kinds of pumps used in central heating systems are simply water movers. They are not pressurisation devices.

 

[BLOD]

Agree with kimbo on this one.

The maximum theoretical heat transfer through 15mm pipe is about 10kw so if the rads need more than this it just isnt going to work.

 

[Henchman76]

Thanks chaps your wisdom is greatly apreaciated. I have only just gone self employed after many years working directly for a firm and I have to come clean now and say that there is an awful lot I havent got a grip on properly. There is an undoubted science to being a heating engineer and its a sharp learning curve , anyway ill stop babbling on. I will certainly look hard at replacing the pipework with 22mm and put it to the client on weds. Thankyou for your words again and goodluck !

 

[doitmyself]

Take some time out and read

Small Bore heating Systems

Copper Tubes in Domestic Heating Systems

 

[Henchman76]

Thanks again chaps. I went back to the scheme yesterday to look again and at more detail at the layout of the heating circuit and I am more or less certain that the main contributing factor in the poor performance of the back half of the scheme is due to iron oxide deposits within the central area of said problem radiators and incorrect bore of pipework (15mm) feeding them. I have purposed to conduct a chemical machine flush over the course of a day and then return the following day and half of the next to replace problem pipework with 22mm. I know that three other firms have priced for the job, two of which have recomended a brand new boiler and have included this in their price. The boiler has an input of 35KW which reduces to 29.7 in actual output which should be sufficient to provide for each and every radiator size present provided all are balanced correctly and are completely cleared of any blockages.

 

[doitmyself]

The boiler has an input of 35KW which reduces to 29.7 in actual output

I assume you are talking about the existing boiler.

Use theBoiler Size Calculator to find out what size boiler is needed. Then check that the rads add up to this or more.