Replacing condensing gas boilers or combi boilers

bob eck

Anyone have photos of heat exchangers cut in 1/2 or 1/3 of condensing gas boiler / combi boilers that have failed that are in less than 10 years. Just wondering what the inside looks like.
Why did these boiler die an early death.
Were they not piped P/S?
Was the primary pump not big enough?
Was the venting not correct?
Was there dirt in the system that clogged the heat exchanger?
Just trying to help my heating customers to install these boilers the best way and for them to last for the home owner.

Harvey Ramer

First and foremost, only buy boilers from manufacturers that pressure test every single hx. I can't stress that enough. I know a certain manufacturer that does this and there are a certain percentage of leaking hx's right from the hx manufacturers. This leak will typically be on the inside and run right down into the condensate pump. This type of leak can easily go unnoticed.
Any leak in the system, allowing fresh water to be introduced, will kill these hx's quicker than anything. The higher temp they are running, the quicker they will go.

Henry

PM me your email. I probably have some. Some are not HX failures but are maintenance failures that caused all sort of damages!

hot_rod

I'd say by far fluid quality is what causes early failure. Some times within the first year. Doesn't matter the type of boiler or brand.

I'm hearing rumors out there that fire tube designs are showing as many or more failures than the spiral tube. What's your experience?

Having the water outside the tube really doesn't change the failure mechanism where the heat from the flame is "insulated" away from the fluid by scale build up. There is not a lot of metal thickness to provide protection against abuse, compared to the old cast iron beasts

kcopp

Here is a leaker. Cosmogas.

bob eck

> @kcopp said:
> Here is a leaker. Cosmogas

Thanks

Is this boiler instalked America or England?
How long was it in?

kcopp

That's in NH. 3 years. City water. AKA... Embassy Onex/ Peerless 160 combi and a few others have rebadged it.

bob eck

Was the boiler in a radiant system or a system with pex tubing? Did the pex tubing have an oxygen barrier.
I thought pex tubing with an oxygen barrier if you are always running high water temps the oxygen barrier is less effective.
Was it piped P/S?
Was the pump big enough?

kcopp

Copper fin tube.
Very little barrier pex.... Watts
Not piped P/S.
Expansion tank was undersized....Too much make up water introduced.