New gas boiler install what kind of liner?

chrisrhit

if i am getting a new 140k btu hydronic boiler installed to replace my old one from 1960 and have an old clay chimney liner what kind of new liner would i be able to get for this? Aluminum or stainless steel?

Bob Harper

Aluminum is approved for CAT I gas venting. However, it doesn't last and is a very poor choice. The listing only requires a 100lb dead load on alum vs. 200# on ss. There is no brush test of 100 strokes with a tight fitting wire brush as with ss. You do not have to insulate either liner. There is much fuss about insulating heater liners. If you seal the top and bottom of the liner and the chimney is otherwise not leaking, you create a Dewar's Flask, which insulates like a Thermos bottle.
Oil can only use 316 ss

chrisrhit

ok cool thx!

leonz

If the clay liner is intact there is no reason you cannot use it.
If you are worried hire a chimney sweep to inspect and clean
your existing chimney and install the proper chimney cap.

EBEBRATT-Ed

@leonz

That is just not true.

Depends on the location and outdoor air temperature and weather it is an inside or outside chimney the btu input and the clay liner size and weather there are any other appliances using the chimney. Look at the gas code and venting tables. In most cases a liner will need to be installed.

EdTheHeaterMan

leonz said:

If the clay liner is intact there is no reason you cannot use it.
If you are worried hire a chimney sweep to inspect and clean
your existing chimney and install the proper chimney cap.

This might depend on how tall your chimney is. The metal liners will heat up much faster since the thickness of any metal liner is relatively tiny compared to the amount of mass that a masonry chimney has. Think of it like this, How many BTUs will it take to heat up one brick v. one 4"x 8" area of sheet metal? The brick will take longer to heat up and will take longer to cool down. Now think about how many bricks there are in one chimney and how much heat will be absorbed by those bricks before the top of the chimney will get hot enough to stop flue gas condensation? That may take 20 minutes on a 4 story tall chimney, and if the heating cycle is less than 15 minutes, the top of the chimney will always have a condensation problem.

If you live in a ranch home on a slab foundation, then your chimney is much shorter, and the top will get hot somewhat faster.

If you have a metal liner made of a thin material like aluminum or Stainless Steel, and you seal the top and bottom to create the Dewar's Flask, the top of the liner will be hot in less than 3 minutes of burner time.

KC_Jones

chrisrhit said:

if i am getting a new 140k btu hydronic boiler installed to replace my old one from 1960 and have an old clay chimney liner what kind of new liner would i be able to get for this? Aluminum or stainless steel?

I know this isn't your question, but I always get concerned when I see some of the boiler sizes mentioned here.

How was it determined that's the appropriate boiler size for your house?

I ask because that's actually a relatively large boiler for a typical single family home. You should be able to heat at least 4000 sq ft, marginal insulation and windows, with a boiler that size. The sizing does not go by square footage, but it can be used as a reference point in situations like this to bring to light a possible oversized boiler situation.

Just a homeowner here trying to assist another homeowner.