Not Sure What to do
I'm finally getting a gas line installed from the main to my house. We're having the oil tank, water heater, and the ancient boiler removed.
I'm looking to buy a new gas boiler to heat the home. I'm not sure if I should look at the combi units or get a separate gas boiler and gas water heater. We live in the North East and have a 2000 sq ft home.
The local gas company is offering the following rebates:
Hot water boiler AFUE 96% - $1,500
Hot water boiler AFUE 90% - $1,000
Hot water boiler AFUE 85% - $500
Combined High-efficiency boiler & water heating unit: Condensing Boiler with on-demand domestic hot water minimum AFUE Rating of 90% - $1,600
High-efficiency indirect water heater - $400
Condensing Gas Water Heater - $500
High-efficiency on demand tankless water heater $800
Should I get the combi and if yes, which brand? Or should I get separate units? I can't seem to find recommendations or ratings for gas boilers. Any help would be appreciated. Thank you
OK first the question of combi or separate units. Personally I am a fan of indirect tank type domestic water heaters. The reasons are that you get the same great efficiency as the boiler provides, the boiler gets used throughout the year, so it is not sitting static all summer, and the indirect tank is easy to service and maintain, where the combi unit is much smaller and saves space, but harder to service.
As for brand, you need to ask your HVAC contractor what they recommend, most contractors are going to recommend a brand that is locally available, with good access to parts. I use several brands here, depending on what features I need for the install. Do I want a SS or aluminum heat exchanger, do I want an integrated pump or external, there are a lot of control options, it all depends on the individual lay out.
As for type of boiler, again it depends on several factors. High efficiency boilers are great, but require good maintenance. Cast iron boilers require less maintenance, and last a long time, but venting and efficiency are an issue. Often I can install a high efficiency boiler for close to the same $ after rebates and tax credits because of things like venting, and stairs that may have to be braced or removed to bring the new boiler into the home. My advice is look for good local contractors and find one that you are comfortable with.
There is a good post in the residential forum on how to pick a contractor. If you are asking for DIY then please read the rules at the top of this forum.
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Originally Posted by Wheelbaron
Again, sizing is very important. Some manufacturer's have combi boilers that reach very high Btu requirements while others limit the size of the combi boilers. If you want a particular manufacturer of boiler (I do like the Triangle Tube personally in our area) and they don't make a combi in the size you need, then doing the boiler with an indirect water heater is my suggested solution. FWIW, I'm not a fan of aluminum block boilers. There have been some issues with some of them and I'm just not ready to embrace acidic condensate and aluminum. I prefer the stainless steel boilers. JMO.
Originally Posted by mjohnson267
To the HO, what you didn't post was the most important information that should be taken into consideration when choosing a new heating and water heating system.
1) What kind of radiation does the home have? Is it radiant, large cast iron radiators, fin tube, cast iron baseboard?
2) Is the heating system zoned with multiple thermostats or just one?
3) How do the occupants of the home use hot water? How many people in the home and how often to multiple people need or want to use hot water at the same time?
I can't stress enough that to try and make a unit fit into your unique situation simply because of the highest rebate amount will lead to a multitude of problems, could make the system hard to live with and almost always leads to very expensive repairs and maintenance costs and a short life of the equipment. It's like trying to pound a square peg into a round hole.
Also when replacing your base equipment/boiler is the time to think about the potential upgrades like zoning. To do this afterwards could mean that the boiler you picked is the wrong size. You have time to educate yourself and make an informed decision.
Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.
Navien Combi-gas is a very nice unit - worth looking into.
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Thanks for all the replies. Here is some more info:
House has fin tube radiation
4 zones all with separate thermostats
House is around 2800 sq ft. (800 in finished basement, 1000 on 1st and 1000 on 2nd floor)
There are 4 people in the adults with no more than 2 showers going at the same time.
Thanks for any info you provide.