Central heating not circulating after New Navien Combi fitted to Santon Premier system.

[JohnHuson]

Yes I agree completely. However I suggest separation, pumps in series is not always going to work.

You are magic and clever so thank you.

 

[JohnHuson]

So where should we install the extra pump please?

 

[ShaunCorbs]

After the external heating plate heat exchanger which will need to be added

 

[SJB060685]

You're going to need to separate the system and as Shaun says a plate heat exchanger is your best bet as it will protect the boiler circuit from your decades old and no doubt fouled system. once you separated then a suitable pump will be installed on the flow out of secondary side of the plate heat exchanger.
At this point I strongly urge you to find a firm/engineer who understands the principles of hydronic system design.

 

[JohnHuson]

After the external heating plate heat exchanger which will need to be added

That is also my logic and I thank you for your help. If the boiler produces hot water and the circulatory system
is free to flow then all that is required is to pump it around?

 

[ShaunCorbs]

Close enough

 

[JohnHuson]

I have a qualified engineer arriving tomorrow afternoon. Thank you for your input! John.

 

[SJB060685]

A pump is required to supply the pressure required and the flow rate required. It's actually the system that creates the pressure but the pump has to be able to meet demand. As it stands the boiler integral pump just can't do this.

 

[ShaunCorbs]

I have a qualified engineer arriving tomorrow afternoon. Thank you for your input! John.

Do they do commercial heating systems ?

 

[SJB060685]

Close enough

As you said close enough mate but I must add if the secondary side is staying open vented then pump in that image is not situated ideally. One would need it to be V,C,P on the flow out on secondary side.