Question for a poor system design

[GQuigley67]

Hey folks been a while since I've posted on here looking for advice but this one is a bit of a pain. Here's the scenario.

Guest House with 4 open vented boilers, 2x U6 meters feeding 2x 24kw HE Greenstar Ri boilers.

One of the systems has poor circulation I changed the motor on the pump as the water was clear and the magnetic filter(installed 8 months ago) didn't have much sludge on it not enough to cause alarm, but ... it was installed on the flow before the pump. I tested the pumps resistance and it was 370ohms at speed 3, so thought replacing it might work but didn't.

Now this one 24kw boiler is feeding 2 HWCs and about 20 radiators with 4 stories. 22mm Flows and Returns, no Diverter valves, and no regulation valves apart from lockshields on radiators. Flow up to heating as hot as I can feel, flow to HWCs hot but HWC returns stone cold, CH Return luke warm. Cylinders are older than radiators and showing signs of corrosion, Radiators replaced 7 years ago.

Systems been working fine for 7 years apparently. I disagree... seems undersized to me, or possible blockage somewhere... so would like some opinions.

Also would removing the new pump head to keep for spares become useless over time through corrosion or any tricks to preserve it.

 

[lame plumber]

whats the other boiler doing?

 

[GQuigley67]

its all separate systems there's 60 rooms in the place only this boiler forget the other 3

 

[GQuigley67]

boiler isn't overheating or anything the boiler is fine running efficiently

 

[Dotty]

I'll say it then......

Welcome back Gerry!

 

[kris]

Hi there. When you've hot water only on is the return still cold . Sounds like air locks

 

[kris]

How old are the cylinders and are both coils no heating ?

 

[GQuigley67]

No diverter valves on the system, they must just turn radiators off in summer.

 

[GQuigley67]

manual air valve on cylinder coil was water, cylinders look 20+

 

[kris]

Be ideal with ZV or regulator valves or similar as its a load of rads to run round and shut off to force through coil lol.. Defo circulation issue it's jusa case whether its air or furred pipes , like u said the filter was quite clear ....

 

[GQuigley67]

Tomorrows gonna be fun! hahaha

 

[GQuigley67]

Seems to have fixed itself over night, lost one of the Allen screws for the grundfos pump though, anyone know where I could get spares or is it a case of going to the scrapies?