Hot Water Boiler System - Weil Mcclain

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Old 10-14-10, 05:58 AM
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Hot Water Boiler System - Weil Mcclain

I need a new gas fired boiler to heat my 1200 sf house and the big HVAC company in my area carries Weil-Mcclain Ultra - im looking at the high efficiency units. There are a few plumbers in the area that install boilers as well but their costs were significantly higher. I received a quote for about $6000 for installation of the WM boiler.

- Are high efficiency boilers preferred right now because of the cost savings or are there still "kinks" to be worked out internally with these units?

- With the WM unit, can a new hot water heater be used in tandem with the boiler to increase the efficiency of hot water usage in my home?

- I'd like to do a heat loss calcultation in my home before I decide on the installation. When they estimated the cost of installation the salesperson just looked at the output of my old boiler to decide the output of the new boiler. I think it was 100,000 btu. Is there a link to a "how to" do a heat loss calculation and will it provide me with the correct btu output for my home?

- Are the new boilers as efficient as they seem? We currently have a Roberts-Gordon boiler from the 1970's (i think).
 
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Old 10-14-10, 08:21 AM
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The Slant/Fin program is popular: http://forum.doityourself.com/boiler...alculator.html
 
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Old 10-14-10, 08:54 AM
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If you want high efficiency for heating domestic hot water, the way to do it is with an indirect water heater coupled to a high-efficiency boiler. The W-M Gold and Ultra lines of indirect heaters are very good (that's what I'm currently installing). As to the W-M Ultra boiler itself, when I was researching my boiler I found that it was much more expensive than much of the competition, while not really offering anything that other manufacturers didn't.

I went with the Triangle Tube Solo, which has excellent reviews and was much cheaper than the W-M Ultra. There are other good brands out there, poke around this forum, you'll see lots of discussion.

One thing to keep in mind is that if you aren't doing the install/service/support yourself, you want to pick a brand that has good local support. Brand X may make the best boiler in the world, but if no one for 100 miles from you sells or services Brand X, perhaps a different choice would be better.

One other thought - what are your heat emitters like? Are you using radiant floors? Fin-tube baseboards? Something else?

The reason I ask, is that the modern high-efficiency mod/con boilers are super efficient only when operating at relative low return water temperatures. There are several ways to achieve this - radiant floor heating uses lower temperature and is therefore a natural choice. Outdoor reset will keep the temp low most of the year, giving you high efficiency most of the time. There are also some tricks you can play with rate of flow to make the returning water cooler, but I don't really know those as well.

If you aren't doing any of the above - just sending the boiler output into fin-tube baseboards, you'll probably realize very little efficiency gains compared to a conventional boiler.

Personally, I have cast iron baseboards, and am using outdoor reset to keep the temps low. Most of the mod/con boilers have built-in outdoor reset, or you can get an external reset controller (such as the ones made by Tekmar), which may have more features.
 
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Old 10-14-10, 09:52 AM
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Another way to do heat loss calcs is here:

http://forum.doityourself.com/members/105376-kolias
 
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Old 10-14-10, 09:56 AM
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Sorry, wrong link above. This may work better

http://forum.doityourself.com/boiler...ml#post1775860
 
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Old 10-15-10, 06:07 AM
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Thanks for the help so far. I have aluminum fin baseboards throughout my house. A small portion of the house that was an addition is on a concrete slab and im planning on installing radiant heat in that area. When I update my system, would it be a good idea to replace the baseboards?

I live in a rural area and the only large HVAC supplier installs weil-mcclain. There are several "plumbing and heating" stores that are companies with 6-10 employees and they do installations. I have gotten 3 quotes so far and one place carried Weil Mcclain and the other carried munchkin. I've read that installation of high-efficiency units can be rather tricky, so I wont be installing the system myself, but should I trust a plumbing and heating shop to do a satisfactory job? Sometimes it can be hard to find skilled labor around here.

I need to do a bit more research on a indirect heater-boiler system, but I think thats the way I want to go.
 
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