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

[SJB060685]

Yep

Low loss header

Then if the old boiler was running at ∆T 11°c the pump would of been capable of the higher flow rate and pressure required to overcome index circuit.
Sounds like this needs a low loss header and suitably sized secondary pump. The secondary side pipework will be ok in size but the new boiler internal pump isn't capable.
Alarming really as the installer really should have considered this 🤔

 

[ShaunCorbs]

Then if the old boiler was running at ∆T 11°c the pump would of been capable of the higher flow rate and pressure required to overcome index circuit.
Sounds like this needs a low loss header and suitably sized secondary pump. The secondary side pipework will be ok in size but the new boiler internal pump isn't capable.
Alarming really as the installer really should have considered this 🤔

Makes you laugh tho they thought a 15-70 would do 2” pipework it’s the state of the industry atm either people don’t care or they don’t know chances are it was a 25-80 or 32-80

Was he even commercially qualified to work on the install

 

[JohnHuson]

Then if the old boiler was running at ∆T 11°c the pump would of been capable of the higher flow rate and pressure required to overcome index circuit.
Sounds like this needs a low loss header and suitably sized secondary pump. The secondary side pipework will be ok in size but the new boiler internal pump isn't capable.
Alarming really as the installer really should have considered this 🤔

I agree. The boiler developed a leak from the heat exchanger seal 9 weeks in and charged 200 quid to do a 35
minute job under guarantee. Now they do not want to know.

 

[ShaunCorbs]

I agree. The boiler developed a leak from the heat exchanger seal 9 weeks in and charged 200 quid to do a 35
minute job under guarantee. Now they do not want to know.

Didn’t they call the manufacturer out ?

 

[JohnHuson]

No and the customer got a gas certificate but the commissioning report was not completed.

 

[SJB060685]

I agree. The boiler developed a leak from the heat exchanger seal 9 weeks in and charged 200 quid to do a 35
minute job under guarantee. Now they do not want to know.

That would of been a warranty job and the manufacturer liable for payment, not you!
Unfortunately to rectify this is going to cost more and the situation clearly demonstrates the installer doesn't understand the principles.

 

[ShaunCorbs]

Time to get a solicitor involved

 

[JohnHuson]

That would of been a warranty job and the manufacturer liable for payment, not you!
Unfortunately to rectify this is going to cost more and the situation clearly demonstrates the installer doesn't understand the principles.

This customer is prepared to spend money in excess of what was paid for what should have been paid under
warranty in a small claims court.

 

[JohnHuson]

So where in the system should the extra push pump be located please?

 

[ShaunCorbs]

Where the old boiler pump was

 

[SJB060685]

I think between us we have arrived at the problem. My concern now though is as I mentioned above are the existing rads at ∆T 60°c, if so the flow temperature will need to be around 90°c to give a rad MWT temperature of 80°c and full out put.

 

[JohnHuson]

I think between us we have arrived at the problem. My concern now though is as I mentioned above are the existing rads at ∆T 60°c, if so the flow temperature will need to be around 90°c to give a rad MWT temperature of 80°c and full out put.

yes hat makes sense but I have to get the water around the system in the first place.

 

[JohnHuson]

The boiler is capable enough so where do I install a secondary pump?

 

[SJB060685]

yes hat makes sense but I have to get the water around the system in the first place.

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

 

[ShaunCorbs]

Post 35

 

[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.