Older home needs hot water heater replacement


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Old 07-27-06, 08:07 PM
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Older home needs hot water heater replacement

Ok guys, I'm no piker, and I've replaced my own boiler once before (former Chemical Engineer), but I want to hear about issues related to attempting to replace a boiler with a "high efficiency" boiler. For instance, is it absolutely necessary to re-line the effluent stack with stainless steel to reduce the changes of a chimney collapse ? I've heard that hi-efficiency heaters really put-out some nasty stuff into the air and that "kills" most terracotta-lined chimneys very quickly.
Other than that, and the dreaded bleeding and re-filling part of the job, what else should I be worried about ?
 
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Old 07-28-06, 05:21 PM
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High Efficiency Boiler

Are we talking oil or gas fired? Any potential models you've selected?
 
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Old 08-01-06, 08:45 AM
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Originally Posted by marksimms
For instance, is it absolutely necessary to re-line the effluent stack with stainless steel to reduce the changes of a chimney collapse ? I've heard that hi-efficiency heaters really put-out some nasty stuff into the air and that "kills" most terracotta-lined chimneys very quickly.
Other than that, and the dreaded bleeding and re-filling part of the job, what else should I be worried about ?
I'm in the process right now. So far, I've got two estimates come back to me.

An 87% high-efficiency requires a stainless steel vent through the wall, as well as air intake. This is because these boilers produce too much acidic condensation, which devours the mortar. So, the "lower" high efficiencies require stainless steel tubes that are pitched in such a way as to drain the condensates. The above 90% efficiencies use PVC piping.

I asked about sending the metal tube up the length of the chimney, and the contractor suggested a special condensation catch-and-reclaim system needs to be installed at the bottom of the pipe, as well as a filtering system. Over all, he said its cheaper to drill a 4" hole through concrete.

I was quoted $8880 and $8925 by two diff. contractors. The boiler costs $2059 at the plumbing supply place, and the indirect heater costs $995. Two circulators are what, $300 apiece? So, $3700 for equipment and $6300 for "labor."

I'm doing the math to see how long it takes to pay off these prices in gas savings.

J
 
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Old 08-01-06, 03:01 PM
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High-efficiency units do not put out more "nasty stuff" than lower efficiency units. What the higher efficiency units do is exhaust at lower temperatures (hence their higher efficiencies) and the "nasty stuff" that exhusts at a lower temperature will condense in the chimney or exhaust vent.

In the lower efficiency (higher exhaust temperature) units this condensation of the "nasty stuff" did not happen until the products of combustion had left the chimney and dispersed in the outside air. In the higher efficiency units it condenses in the chimney (or in the case of 90%+ efficient units in the final stages of the heat exchanger) creating an acidic water that corrodes everything it touches.

This is why the chimneys deteriorate and why PVC plastic is used for sidewall venting of 90%+ units. ALWAYS make sure the drains are properly installed in the exhaust vents of any 90%+ unit and always be sure that the drains are open.
 
 

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