Is the boiler big enough?

[hoylez]

I've installed a worcester 35kw system boiler on a system with 22 radiators it's quite a big property boiler can cope with 119000 btu and I'm using 95000 btu with the rads and hot water
All upstairs rads get red hot and all but 4 downstairs get warm but the 4 furthest from the boiler don't get warm unless I turn all upstairs off the flows are always red hot but return are cold
Anyone got any ideas?

 

[king of pipes]

Pipe sizing ?? 22 mm is not big enough the pump is running out of power 22 rads is to much resistance , low loss header bigger pump ?? Guess work but sure other will have a opinion. Kop

 

[hoylez]

Pipe sizing ?? 22 mm is not big enough the pump is running out of power 22 rads is to much resistance , low loss header bigger pump ?? Guess work but sure other will have a opinion. Kop

Yea it's 22mm the boiler has moved location and the house was 2 houses that have been converted to 1. It's mostly original pipework which I was,unable to get to for various reasons so could be a rite mess under the floor
Do you think with 28mm pipe on the main run the boiler would cope with it?

 

[king of pipes]

Yes 28mm for a good part of the system it's no point doing half a job bud . Kop
[automerge]1605813016[/automerge]

 

[SJB060685]

22mm is too small. You need to up to 28mm. If the pump is able to overcome the index circuit resistance then its not lack of pump head, its the loss of flow rates due to inadequate pipe sizing most likely.

 

[oz-plumber]

Have you tried balancing the system through the lockshield valves.
This may help.

If that doesn't work: LLH with larger pump.
The system may need some tweaking , but may save upgrading pipework

 

[John.g]

Just trying a few numbers.
That boiler probably has a 7M pump and if one assumes a flow rate of 30LPM then there should be ~ 2M head still available after flowing through say 30M of 22M pipework so balancing should probably get all the rads working and also a balancing valve on the cylinder coil will possibly help even more, also timing the HW zone valve to open earlier in the morning before the central heating is required.

 

[EvilDrPorkChop]

Stick a Grunfos UPS 25-80 pump on. That'll sort it out.

Probably needs a low loss header too.

 

[SJB060685]

Hydronic separation is all well and good and serves it purpose but its not always needed.
First I would try balancing the system.
Then I would reconsider the primary pipe sizes before hydronic separation. My initial calculations say 28mm is needed to maintain delta t 20 across and supply flow rates to system.

 

[cr0ft]

22mm pipework has a heat capacity of 40.2KW so the 28mm pipework is unnecessary in my humble opinion.

This is one of three things: -

1.) Blocked/incorrectly sized pipework.
2.) Pump not powerful enough (unlikely as the pumps in boilers are usually sized to be generous enough that you don't need to upgrade them).
3.) Balancing, very likely from what you are saying (upstairs rads very hot compared to downstairs). Have you tried to balance it yet?