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

[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.

 

[JohnHuson]

What nice giving people you all are. Thank you. You really can effect peoples lives by your contribution.

 

[ShaunCorbs]

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.

If it’s a combi it’s sealed or they’ve linked the pressure switch out as navs can’t be run ov

 

[SJB060685]

We do this because we are passionate about our industry, unfortunately for your friend he employed the services of someone who quite frankly doesn't know the basics and as Shaun mentioned before that's damaging.

 

[JohnHuson]

Do they do commercial heating systems ?

Not sure but will check out. There appears to be a vast misunderstanding what the roles are between plumbers, heating engineers,
central heating specialists.

 

[SJB060685]

If it’s a combi it’s sealed or they’ve linked the pressure switch out as navs can’t be run ov

Yes. So in that case if secondary side is sealed as well then a vessel of suitable size is required.

 

[ShaunCorbs]

Not sure but will check out. There appears to be a vast misunderstanding what the roles are between plumbers, heating engineers,
central heating specialists.

When your there tomorrow grab a couple of pictures of the set up

 

[JohnHuson]

We do this because we are passionate about our industry, unfortunately for your friend he employed the services of someone who quite frankly doesn't know the basics and as Shaun mentioned before that's damaging.

Yes, life is full of givers and takers. I find it easier to be a giver as I sleep soundly.
Well done for sorting out my problem.

 

[JohnHuson]

Will take photo's tomorrow.

 

[SJB060685]

Yes, life is full of givers and takers. I find it easier to be a giver as I sleep soundly.
Well done for sorting out my problem.

We've arrived at the problem and can advise on the possible solutions but ultimately it's down to you to find a suitable engineer. Unfortunately knowledge and experience comes at a price, something you and your friend have now discovered.
Can I ask, you said your friend was charged just over 2k, was that supply and fit?

 

[JohnHuson]

We've arrived at the problem and can advise on the possible solutions but ultimately it's down to you to find a suitable engineer. Unfortunately knowledge and experience comes at a price, something you and your friend have now discovered.
Can I ask, you said your friend was charged just over 2k, was that supply and fit?

£2400 supply and fit but did not supply commission document or make the system work. They said that the lack
of circulation was due to knackered TRV's and said we would need to pay an extra £1300 to replace the 23 valves
and make the system work as it should.
I agree to the logic that we need to ensure the hot water is pumped around to reach the extremities of the system.

 

[SJB060685]

£2400 to supply, fit and commission a boiler is really quite low, let alone not sign the necessary paperwork. I can tell you right here and right now that £1300 on new trv's will not solve your issue and had you agreed to that you would still be where you are now. These guys who undertook the work really don't know what they're on about and I genuinely feel your pain.
We've given you all the information you need to move forward. Make sure the new technician that attends is fully aware of the problem and everything we have discussed and hopefully they get you sorted.
Note for the future, an installer/engineer who charges pennies for a job should not be trusted.

 

[JohnHuson]

Than you.

£2400 to supply, fit and commission a boiler is really quite low, let alone not sign the necessary paperwork. I can tell you right here and right now that £1300 on new trv's will not solve your issue and had you agreed to that you would still be where you are now. These guys who undertook the work really don't know what they're on about and I genuinely feel your pain.
We've given you all the information you need to move forward. Make sure the new technician that attends is fully aware of the problem and everything we have discussed and hopefully they get you sorted.
Note for the future, an installer/engineer who charges pennies for a job should not be trusted.

 

[ShaunCorbs]

Any update?

 

[JohnHuson]

I have spoken to an extremely efficient Navien technical advisor and it seems the boiler is capable of providing
the output as needed.
The next step is to balance the system yet again.
I think the system requires a shunt pump to provide the heat to rads 10 metres away. It needs a low loss header?
And hydrallicly balanced? (cant spell that)
My logic is that now the boiler is capable the heat needs moving around the system.
It may even require two pumps around the two levels?

 

[SJB060685]

By the sounds of it the residual pump head after pumping through the boiler heat exchanger is not enough to overcome your index circuit resistance which is why you're experiencing the problems you are. You could either add a LLH and additional correctly sized pump or CCT's and pump. If the secondary side is the same flow rate as the boiler either will work, you just need additional pressure to circulate around the system. Adding pumps in series is not a good idea.

 

[JohnHuson]

I would add that so far my dealings with Navien UK have been superb. Helpful staff and a good
well built product.

 

[ShaunCorbs]

What did the heating engineer say ?

 

[JohnHuson]

By the sounds of it the residual pump head after pumping through the boiler heat exchanger is not enough to overcome your index circuit resistance which is why you're experiencing the problems you are. You could either add a LLH and additional correctly sized pump or CCT's and pump. If the secondary side is the same flow rate as the boiler either will work, you just need additional pressure to circulate around the system. Adding pumps in series is not a good idea.

Thanks for that, it makes sense. May I ask what is the reference LLH and CCt's please. I had a local central
heating engineer around to asses the system to add extra whoomph to the system but after an initial visit he is not returning
my calls. They are a good working family, even the young children are doing their bit for the pub/restaurant and I would
like to see them sorted. Cheers, John.

 

[SJB060685]

LLH is a low loss header, or alternatively know as a low velocity header. Both a LLH and CCT's (close coupled tee's) are a means of hydronically/hydraulically separating the systems. This means the two pumps will not affect each others operation. The boiler pump will circulate at its rate and the secondary side pump will draw what it needs to. As your system is just rads the flow rates either side of separation should be the same. The secondary pump is just supplying the pressure needed to overcome your index circuit (the circuit with most resistance).

 

[JohnHuson]

Thanks for that, it makes sense. May I ask what is the reference LLH and CCt's please. I had a local central
heating engineer around to asses the system to add extra whoomph to the system but after an initial visit he is not returning
my calls. They are a good working family, even the young children are doing their bit for the pub/restaurant and I would
like to see them sorted. Cheers, John.

He said that the boiler was capable at 4okw output for the need. he did agree that the output of the inbuilt
pump was not going to provide circulation on two levels at a distance of 10 metres to the extremes.
He suggests a pump for each zone on a low loss header and hydrallicly balanced.