Gas Combi Boiler/Vent sizes?

andymar

I plan on installing a Weil Mclain AquaBalance WMB-80 natural gas combi boiler for h/w baseboard and domestic hot water use in my 2 story total 1440 sq. ft. addition. The installation instruction seem a little confusing saying either a 2 inch or 3 inch vent/air supply separated is acceptable. Has anyone installed one of these/or similar units and can I get away with a 2 inch PVC piping, total length and adjustments for elbows being less than 55 feet.

bulldoglax

Take this any way you want but You should probably hire a professional if the venting portion is the hardest part and you have not even hung the boiler yet.

andymar

Thanks Dog. After wiring and plumbing most of the addition by myself I sort am running out of a little steam. My plan was to get as much of the easy tasks finished as possible to a point where I will need to pay a "professional" his inflated fee. Have a great day and thanks for wasting some more of my precious time. It was a very simple question.

ratio

I'm very expensive, but the prices aren't inflated. I'm just really good. Berating people about "inflated fees" won't make you any friends here. If you want cheap, try the Yellow Pages.

The question you asked depends on what the manual, that you already read, says. Since I haven't read that particular one, I'm guessing, but on the condensing equipment I've installed, you can run 2" up to the limits the mfgr has determined. After that, 3" is required. You may (again, based on my previous experience, not necessarily your application), run 3" at your option; assuming the minimum requirements (if any) have been met. IOW, what does the manual say?

the_donut

andymar said:

Thanks Dog. After wiring and plumbing most of the addition by myself I sort am running out of a little steam. My plan was to get as much of the easy tasks finished as possible to a point where I will need to pay a "professional" his inflated fee. Have a great day and thanks for wasting some more of my precious time. It was a very simple question.

The venting is the easy part of the job imo, that and the gas line. Sizing the system, selecting the components, getting the primary secondary, circulator/s, bypass and all the connections to the radiators is the hard part that you would normally want a pro for.

Boiler manual specifies 12% derate for 2” and 4.2% at maximum distance (100’).

bulldoglax

> @andymar said:
> Thanks Dog. After wiring and plumbing most of the addition by myself I sort am running out of a little steam. My plan was to get as much of the easy tasks finished as possible to a point where I will need to pay a "professional" his inflated fee. Have a great day and thanks for wasting some more of my precious time. It was a very simple question.


That seems like a solid plan Andy. Also, if you can’t figure out the venting you shouldn’t be installing the boiler. Don’t forget to pipe the primary in 3/4 because that’s the size tapping it comes with!

Henry

DIY is not one that we will connect or do anything until it fails. And then we will charge the "inflated fee" to correct the installation or refuse to do anything. I get architects that do their own radiant and want me to supply and install a boiler. I ask them, did you get the piping diagram from a manufacturer? Nope! So Nope and good luck if it works!

andymar

Ratio, thank you for your answer. Perhaps I should have used the term "premium fees" as in paying a premium price based on the difficulty in the northeast of find a good honest tradesman, of which this country unfortunately has a serious lack of. I by no means meant to berate anyone. College is not for all these kids.
And donut, thank you also for your input. I do know my limitations and will have a professional complete the assembly.
For others that have responded, have a great day and thanks for the chuckle.