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Need to Replace a 1997 Weil-McClain Boiler with High Efficiency

Greetings, I am a homeowner. I live in a 1500 sq ft older home in Chicago. My chimney liner is rusting (at 20 years) and my thought was to have it replaced. But after talking to the hvac contractor he suggested replacing my current 1997 Weil-McClain Boiler with high efficiency and side vent to my backyard. My hot wtr heater is 20 years old and would be replaced by a tank connected to the new boiler, as my understanding. Neither my current boiler or my hot wtr heater is causing problems. I think the boiler technically has another 10-15 years if all goes ok. But I'm open to the new efficiency boiler and side venting it so no longer have to deal with the chimney. I am replacing my roof in spring. My question is can anyone recommend high efficiency boilers? I spend part of my winters out of town so I definitely need one that won't fail me. Reliability is a must, like with most of us. My contractor suggested Prestige Solo but online reviews don't look that great. Perhaps they have better models than others. I asked about high efficiency for Weil-McClain and he said it was not their strength. Though I do see them advertised online. I just want to make sure I don't select the maker based upon the contractor cause he gets promoted for suggesting/selling them. Which I'm not opposed to but again they have to be reliable. Thank you in advance for your help.

Comments

  • Peter_26
    Peter_26 Member Posts: 127
    How bad is the liner that you think it needs replacing? Did your contractor tell you it needs replacing ASAP? If your current boiler been has been reliable for 20+ years then why would you want to replace it? I think if ain't broke don't fix it. Things are certainly not made like they use to be.

    If you decide to go with a new high efficiency boiler, no matter what brand it is, make sure he performs a heat loss of your home and sizes the equipment properly.

    My 2 cents
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,430
    What’s the annual gas usage? And what kind fob emitters do you have - baseboard, radiator, radiant floors, etc?
  • WMno57
    WMno57 Member Posts: 883
    1. Get an new electric resistance or heat pump water heater.
    2. Get a new chimney liner (simpler now because electric water heater doesn't need chimney).
    3. Spend all the extra money you saved on fun things.
    Peter_26
  • pecmsg
    pecmsg Member Posts: 4,188

    Greetings, I am a homeowner. I live in a 1500 sq ft older home in Chicago. My chimney liner is rusting (at 20 years) and my thought was to have it replaced. But after talking to the hvac contractor he suggested replacing my current 1997 Weil-McClain Boiler with high efficiency and side vent to my backyard. My hot wtr heater is 20 years old and would be replaced by a tank connected to the new boiler, as my understanding. Neither my current boiler or my hot wtr heater is causing problems. I think the boiler technically has another 10-15 years if all goes ok. But I'm open to the new efficiency boiler and side venting it so no longer have to deal with the chimney. I am replacing my roof in spring. My question is can anyone recommend high efficiency boilers? I spend part of my winters out of town so I definitely need one that won't fail me. Reliability is a must, like with most of us. My contractor suggested Prestige Solo but online reviews don't look that great. Perhaps they have better models than others. I asked about high efficiency for Weil-McClain and he said it was not their strength. Though I do see them advertised online. I just want to make sure I don't select the maker based upon the contractor cause he gets promoted for suggesting/selling them. Which I'm not opposed to but again they have to be reliable. Thank you in advance for your help.

    Thats a reason to stay Low efficiency!

    Keep in mind that the High Efficiency is achieved only when the return water is below 140°F. Your current boiler probably runs at 145 -160° return water.

    The liners gone, WHY? Replace the liner with stainless steel. Much cheaper than a new boiler.
    Peter_26
  • jeffyurkanin
    jeffyurkanin Member Posts: 3
    Thank you all for your replies. Some add'l info on my end.

    My current boiler is a Weil McClain CG-4 Series 12 installed in 1997 and said to have a 35 year life.

    Looks like the liner (20 years old) has rusted and debris was plugging up the flue at the elbow which is near the boiler. I think it was galvanized steel. In October another hvac contractor performed maintenance on the boiler and discovered the issue but unfortunately did not replace liners. This hvac guy was very thorough and I learned a lot. The blockage was cleaned out. I'm not sure if the blockage was a result of years of accumulating. I have CO detectors and never went off.

    So I was thinking with the cost of the new liner (guessing $2k-$3k) plus the cost of replacing the water htr why not go the route of a new high efficiency boiler and side vent it. But now with your comments I'm rethinking it.

    My 12 month gas usage looks to be around 770 therms for both boiler and wtr tr. I have 7 old school radiators, work fine.

    I think my boiler runs 160-170 so now I guess high efficiency would not be performed? And the contractor mentioned he would give me the same size as the current boiler which is an input of 105k btu/hr. He did not perform a heat loss.

    I'm in Chicago and have an unfinished basement not within the thermal envelope so would an electric resistance or heat pump water heater still do the job? Any ideas on cost of unit?
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,430
    I think my boiler runs 160-170 so now I guess high efficiency would not be performed? And the contractor mentioned he would give me the same size as the current boiler which is an input of 105k btu/hr. He did not perform a heat loss.


    No, this is commonly misunderstood. Just because the current boiler uses 160 doesn't mean it needs 160 ever. Even if it does, that would be only when it's coldest outside, which is a small percentage of the heating season. So you could certainly be condensing nearly the entire winter.

    Only 770 therms is a small heat loss, but boilers come in limited sizes so a 105kbtu that can turn down to 1/10th it's max is fine. An 80kbtu would be better, but that's splitting hairs.

    Assuming the flue is safe, keeping the existing boiler until it breaks is probably your easiest option.
  • WMno57
    WMno57 Member Posts: 883
    edited November 2022
    I'll answer your last question first.

    I'm in Chicago and have an unfinished basement not within the thermal envelope so would an electric resistance or heat pump water heater still do the job? Any ideas on cost of unit?

    I just replaced a 24 year old 40 gallon natural gas water in my son's Chicago area home. We replaced like for like. This home had a lot of winter inactivity over the years like your home. The wye tee connecting the water heater flue to the main flue was rusted out. Basic gas water heaters condense and rot out flues in homes that get vacation type use.
    Get a tank type water heater, not a tankless. Chicago water is too cold for a tankless.
    I like electric resistance tank water heaters because they are cheap and simple. I have one in my home. They cost more to operate, but if you are a small family with normal hot water usage, you will come out ahead.
    Heat pump water heaters are an interesting new option on the market. Your home with limited winter use may be an ideal situation for one. They dehumidify the basement and make hot water. So you kill two birds with one kilowatt.
    We don't talk labor prices, but the big box stores have electric resistance water heaters for $500 and HPWH for $2000. Either will require a new 240 volt breaker in your electrical panel.
    MikeAmann
  • jeffyurkanin
    jeffyurkanin Member Posts: 3
    Thanks again for all your input. It's very helpful in deciding a good path forward.
  • pedmec
    pedmec Member Posts: 719
    If you have radiators i would definitely consider a condensing boiler. Radiators and condensing boilers are the perfect combination if you looking for maximum savings. With a rotted out chimney liner its sounds like your boiler as been running on low system temperatures already.
  • BobZmuda
    BobZmuda Member Posts: 23
    edited November 2022
    A heat pump water heater will make your basement even colder. Depending on the winter temps in there that may be a problem. 

    As far as boiler size and efficiency goes:  I see the maximum btu output talked about a lot in regards to sizing.  It needs to be big enough to supply enough heat for your house.  But What’s most important for efficiency is the minimum.  Say your heat loss analysis comes back at 60,000 btus an hour. You can have a 60,000 btu an hour boiler be oversized while a 140,000 btu boiler may not be.  All depends on the minimum firing rate.  If the 60,000 btu an hour boiler has no turndown it’ll be oversized 95% of the time.  If the 140,000 btu boiler can fire at 14,000 btus an hour it is actually sized much better for everyday use. An 80,000btu an hour boiler with a 5-1 turndown will have a minimum firing rate of 16,000 btus an hour.  Again, the 10-1 turndown 140,000 btu an hour boiler is actually a better fit. Most modern boilers can also have their firing rate limited. 

    Considering you have cast iron radiators I’m going to assume some insulation, air sealing, or better windows have been added over the years.  That means that you’re likely over radiated, which is a good thing. It means your supply temps can be lower.  Without lower supply temps your “high efficiency” boiler will have no better an efficiency. 

    Which means a manual j heat loss analysis should be performed and radiation figured out so you can pick a maximum water temp as low as possible.  Then you add an outdoor reset sensor and 95% of the time it will be supplying less than the maximum water temp.  More flue gases will condense which releases the latent heat in them which means you might actually see that 95% combustion efficiency in the advertising. 

    I would skip the heat pump in the cold basement (fyi efficiency is less the colder the room they’re in) and would get quotes for a new liner and a quote for a new boiler with an indirect for ultimate reliability or a combi for inexpensiveness.  Keeping the boiler and water heater with a new liner is not a bad option if the price is right.  New boiler will likely last 20 years.