boiler replacement, small apt building


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Old 01-08-11, 07:57 AM
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boiler replacement, small apt building

we are considering a boiler replacement and i would like to get more educated.

recirculating hot water, gas fired, in the basement with Heat Timer control, five story, ten unit condominium, brick building (c 1850), about 1000 sq ft per apartment, average 2-1/2 people per apartment
the present boiler has been in service since the early 1980's and is having ignition problems and parts are difficult to find (according to our heating tech, who has the maintenance contract). They have suggested a boiler replacement.

any advice on newer systems, can we also combine domestic hot water production as well, since it seems our domestic hot water heater, a commercial unit, may need replacement as well?

regarding domestic hot water:
for example, It occurred to me that a 100 gallon storage tank on the input side of the hot water heater (also gas fired) would raise incoming water to ambient, reducing the heat requirement. Also a heat exchanger in the domestic boiler tank so some of the heating system energy could assist.

located in New York City, where we get a pretty hearty winter season

thanks
 
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Old 01-08-11, 08:49 AM
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I would probably try and repair what you have. Boiler parts are basic controls and are not all that different from one boiler to the next.

If your going to change I would go with several smaller boilers Couple that with some indirect HW and your good.
 
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Old 01-08-11, 11:34 AM
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You should go with indirect water heaters. They basically are just water tanks that are treated like heating zones. When they need to be heated, the boiler fires up and circulates hot water through a heating coil inside the tank. It is the most efficient way to make hot water.
 
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Old 01-08-11, 05:42 PM
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Originally Posted by jmilich View Post
any advice on newer systems, can we also combine domestic hot water production as well, since it seems our domestic hot water heater, a commercial unit, may need replacement as well?
First piece of advice is to do a heat-loss on the building. Use a program like Flopro Designer from Taco...it's free

A 20 year old boiler is not that old, sure your repair tech just doesn't like old tech.
 
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Old 01-08-11, 05:51 PM
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Originally Posted by grumpy_guy View Post
A 20-year-old boiler is not that old, sure your repair tech just doesn't like old tech.
Plumbers that sell boilers - best to avoid. And, in NYC? Sorry.
 
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Old 01-08-11, 06:17 PM
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80s boiler ought to have a bit more life in it, but not unreasonable to start planning for replacement. Heat loss calculation and calculation of times and amounts of DHW demands to start.

While planning, do whatever you can to tighten the building envelope by insulating and air sealing. That will most likely be more cost effective and save more energy than new boiler and DWH system.

When you do eventually go new boiler(s), as other mentioned an indirect or two is a good way to go. For multi-unit apartment, look at staged modulating-condensing boilers. They will do a great job handling variable loads and are a fine match for doing DHW duty as well. Major modcon manufacturers often build in the staging controls for this kind of application. Lochinvar Knight is a good place to start looking.
 
 

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