Mass 2003 venting laws

Mitch_6

in 2003 on an exposed masonry chimny with terracotta liner.

Free standing gas water heater and cast iron conventional draft boiler with electronic ignition.

Have a customer that had an install done and the liner is now flaking apart to a point it blocked the breach of the flue.

Mitch S.

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John_140

What's happening and how to fix it.

Not sure about Massachusetts minimum requirements, but the reason you are seeing this problem is that the newer gas units don't have a stack temp as high as the older oil/coal fired units did. An external chimney will be very cold and so the flue gasses lose heat as they exit. Older oil boilers might have a flue gas temp of 350F to 450F. More than enough heat to make it out of a typical chimney. The older system may also have run longer to maintain heat in the building, keeping the chimney nice and warm.

Modern gas boilers have stack temps that can be as low as 250F to 325F, and should run less often. Not enough to keep the chimney warm between firings. Add to that the independent gas water heater (about 45,000 BTU, probably not enough to get out on it's own during the winter) and you have a setup that will tend to condense in the chimney and damage the liner. Essentially you are seeing the results of acid rain inside your chimney.

Solution: appropriately sized flue liner. Possibly two, one for the boiler and one for the hot water heater, depending on space. Use B-vent or equivalent. Depending on your weather you may want to go for the extra to cover insulating around the exterior of the liner.

Mitch_6

Yes I know how and why

The question is what was code at that time. I typically have Stainless liners installed in all my exterior flue applications. The code has been back and forth for a while and what I am looking for is what was the code the day the boiler was installed.

Mitch S.

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Chris_82

once,...

The code is an evolving changing thing more than once I have heard about people wanting to go back in time to support arguments about this or that or my favorite one about how having an inspection, gets the company or the installer off the hook because an inspection was performed. Trust me having the inspector sign off on a job doesn’t grantee that all of your work meets the code and therefore the job is now on the inspectors’ conscious and responsibility! If there is a better way that has been learned you have a responsibility to correct or update the job, not the local code authorities. More than a few chimminys have been redone by going back and informing the customer, frequently and politely in writing that stuff learned and we should do this to make it a better job as well as a safer job! As a rule the more you talk about how the code has changed to support earlier work the bigger the hole you make for yourself. Masons still make large openings and flue sizes because they are limited in the materials they have to use, but that is no excuse for combining mixed gases or not lining the larger flue openings with the proper size. All too often individuals will try to make something work when what is needed is a new chimmminy or to start over, there is no justification otherwise.

Bob Harper

the codes

Show me where the codes DON'T require the liner! All chimneys must meet the class of service. Before connecting equipment or changing fuels or efficiencies, you must inspect the chimney to determine if it is suitable for that application. Since all masonry heater flues rot out and everyone knows this, there is no excuse not to reline it. Even with a brand new chimney, the flues are usually oversized as previously pointed out.

Let me state this again on this site for the 10,000th time-- Forget about whether it is an interior or exterior chimney. Reline them all. You show me a chimney you think does not require a liner and I'll buy you a new analyzer if I cannot flunk it based on national chimney inspection standards and the codes.

Failure to reline puts you and you customers at risk. I agree wholeheartedly with the observation about going back and relining old jobs. If you don't want to do it, suggest they call several chimney sweeps who do. Then everybody wins, esp. the homeowner.

Mitch_6

The inspector read to me that in changing fuels

all that is required is the flue to be cleaned and inspected that it is unsuitable order.

The Install was the summer of 2003 by a utility sub.

I got the call monday for no heat and found the liner flakes blocking the breach and the spill switch out for the boiler. The water heater has no such safety and just kept dumping.

The inspector that inspected the original installation said the job was done within code.

Mitch S.

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Mitch_6

Forgot

The exception is only if the manufacture spell out in the installation instructions a metallic liner is needed.

The installation instructions were not left on site.

Mitch S.

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