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Ask Airheatman Your Own Question
Airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 7539
Experience:  Furnace, A/C and heat pump specialist.
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The unlined brick chimney in my 116 year old two family home

Customer Question

The unlined brick chimney in my 116 year old two family home is crumbling and coming apart. Two boilers, each 105K BTU's and two water heaters all vent into this chimney. Trying to figure out what to do. Someone suggested removing the damaged portion in the attic, installing a liner and B venting the rest through the roof. The other option is direct venting out the side walls and eliminate the chimney altogether. I got a 3 estimates, all of them want to put what I think is a rather large 200-225K boiler in. I plan on insulating the attic and basement joist bays so those sizes seem rather large
Submitted: 6 months ago.
Category: HVAC
Expert:  Airheatman replied 6 months ago.
AS for the vents, using the type B and eliminating use of chimney will probably prove best solution.If they are replacing 2 105s with a single 200-225 that should be appropriate.
Customer: replied 6 months ago.
Are direct vent boilers that vent out the side wall
with the inducer fans noisy and problematic?
Expert:  Airheatman replied 6 months ago.
Usually not noisy at all, the termination of course will want to be in a location away from any foot traffic or area such as a porch or deck.
Expert:  Airheatman replied 6 months ago.
AS for problems , most will have warranty for 5 to 10 years
Expert:  HVAC Guru replied 6 months ago.
Hello and thanks for using this service, if you have been waiting do not worry or get upset. I am HVAC Guru an extremely experienced tech on the site and I try to get to as many customers as I can. I just picked up your question now. Answer: I would go the direct venting route as that would be the best option and typically least amount of money. The boiler size really depends on the square footage, but could be right for sure and I would have to say if you have 3 estimates I bet they are right on the size, you always would rather be larger than too small on a boiler system anyways. All I ask is please use the Star Rating Link at the top of your page before leaving, tips are greatly appreciated so thank you very much for using this service. If you have any other questions just post back to me here anytime!
Expert:  Airheatman replied 6 months ago.
PLease disregard the other experts comment. He no doubt can not see that you are already working with me.If you have further questions, please let me know.Thanks for letting me work with you.If my answer has been polite, professional,and thorough, please click one of the ratings before you go. If you still need help let me know!.Expert is not paid for assisting you until you rate answer.Feel free to follow up for 30 days at no additional cost. Bonus always appreciated if you feel justified.To rate answer, please select one of the stars below.
Customer: replied 6 months ago.
I seem to get a lot of different answers on boiler sizing. each apartment is 1000 sq. ft. I will have the attic insulated but the walls have none. Some say 105K input is fine for that size while others say it is way oversized and that I should do a heatloss. Right now there are two boilers and i don't know if it would be cost effective to keep two or just one for the whole building and just include heat in the rental unit.
Expert:  Airheatman replied 6 months ago.
The true way to determine size is ask the contractor to do what is called a manual J load calculation.To begin with, the only way to be sure unit is sized properly is to do a load calculation on the home.THis is known as a Manual J Load Calculation.It is a program where you enter all of the building construction factors such as square footage of home, construction type such as wood frame or brick,how much attic insulation, wall insulation. whether on a slab or up off the ground on peers. the square footage of glass windows and type of windows facing each direction, whether there are covered porches shading windows,number of occupants(figuring 2 per bedroom),number of fireplaces if any, number and type of exterior doors,ceiling types,geographic location and other such factors.For example a 1500 square foot well insulated home with double pane windows on a slab with 8 foot ceilings and very few windows facing east and west (receiving direct sunlight) with 2 bedrooms in North Carolina with an average high summer temperature of might 85 require only a 2 ton unit to properly cool the home where as the same1500 square home in South Alabama with an average high of 95 degrees.with 9 foot ceilings or if not well insulated and had a lot of glass windows facing west or east may require as much as 3 tons to properly cool the home.This takes about an hour and a half to two hours to do a manaual J by entering all the construction factors.Most contractors will run a manual J for about 200.00 and add it to the price of the installation.Many states are requiring the manual J in order for permit to be issued and inspected.This protects the homeowner and guarantees unit is properly sized.
Customer: replied 6 months ago.
One contractor told me the boiler with short cycle if too large and rust the heat exchanger out.
Expert:  Airheatman replied 6 months ago.
That I exactly right. The newer high efficient equipment is more critical than sizing used to be due to the fan assisted vents. I would request the load calculation showing your heat loss before proceding with installation.
Customer: replied 6 months ago.
Also is it more cost effective to use an indirect water heater off the boiler, or should I just install either a stand alone direct or power vented tank?
Expert:  Airheatman replied 6 months ago.
More cost efficient to use the indirect since boiler is already heating the water.
Customer: replied 6 months ago.
Will an indirect last longer than a regular tank?
Expert:  Airheatman replied 6 months ago.
I would expect the indirect.Most of them actually carry a lifetime warranty on tank.