a movement back to water tube mod cons?

ScottSecor

With regard to mod con failures, here is what we've seen (been installing and servicing them since about 2000).
Approximately 150 Giannoni style stainless steel heat exchangers, not one failure (yet) but at least six have been nearly plugged and had to be cleaned. They range in size from 50K BTU to 1.5MBTU.

Approximately 25 W/M aluminum heat exchangers, about eight failures so far. They range in size from 80K BTU to 550K BTU

Of these 175 boilers, we service approximately 70 on an annual basis, cannot speak about the others (not sure if they are serviced at all).

For the past six years almost every commercial installation has been fitted with a hydraulic separator. These seperators get flushed often, especially right after installation. On these same jobs, each boiler is fitted with a wye strainer and it too gets flushed often. On residential installs, we flush the entire system after installation before firing the system then again after a few days of operation.

With regard to swapping a wall hung roughly 80K BTU boiler (with identical unit, assuming it's still manufactured and readily available when needed), I would guess approximately 14 man hours. Besides the new boiler, you would likely need a few other items for venting, condensate, supply and return piping, etc. I'm guessing we have to pick up the new unit and drop off the failed unit.

Henry

What I am seeing is water tube boilers that have small pumps that will provide originaly 40 Delta T are now 45 and 50F delta T. The failures occur around 8 years. They were all installed by other outfits. I had two in the past two weeks that failed and were installed late 2008. They also pipe 500,000 BTU boilers with 1 1/2 inch pipe instead of 2 inch. Therefore more restriction of flow. They use the same boiler pump for the boiler/flate plate heat exchange circuit! we have not had any failure when using 25 F delta T.

NYplumber

Six of one, half dozen of another here where I stand.

For my own homes, in one I installed a cast iron dry base boiler. Simplicity. For the other, an NTI TX series. I couldn't fathom the idea of all those welds in one boiler being installed in my home.
For clients, I usually end up with a fire tube NTI TFT boiler. The control is a bit more complex and they usually have two boilers so one backs the other up in the event of a failure.

I have installed some of the larger wall hung Viessmann boilers and enjoy the short depth of the HX. On the giannoni HX over 399mbh, I find the HX is too long to do a proper cleaning between the tubes especially when the boiler was neglected. Working recently on an 800mbh water tube mod con was not fun (wasn't cleaned in five plus years).

How long till the factory sends the boiler with a glycol/water mix thats pre treated and the end user connects the system piping to the system side of a FPHX?

jumper

Steel water tube manufacturers claimed I can change the tubes. Yah and I can jump off a roof too. Clients with twenty year viewpoint go indirect even for heating. Because over the years raw water will be added to heating system.