System Recommendation

Bruce_20

The boiler and water heater need to be replaced, and I'd appreciate any feedback I could get on whether to buck up for a Buderus mod/con setup.

I live in a 3000 sf single family in Pennsylvania, built in 1929. We have 14 column radiators and three lengths of baseboard dispersed in various parts of the house. The original system was, I assume, a coal-fired gravity system, with the large (3"-4") supply and return mains remaining in the basement. Heat loss calculation is said to be 80,000.

I was quoted $7,800 for a Buderus GB142/30 with ST300 79 gal. indirect fire holding tank.

The Buderus seems like a good system, but I'm wondering whether the size of the pipes makes it less worthwhile to purchase the mod/con boiler over a standard system. Any thoughts would be appreciated.

Steve Ebels_3

You have a system that a M/C boiler thrives on

Don't even think twice about it. Every time I've installed a M/C boiler on a high mass system, the homeowners have reported 30%+ fuel use reduction with most hitting 35-40%.

That being said, correct installation of that Buderus is paramount to your satisfaction with it. Ask your installer about precautions he's going to take regarding system water quality, filters to catch the gunk floating around in the pipes, issues that need to be addressed regarding chemical treatment for PH, that kind of thing. The Bud is a fine piece of equipment but as with any M/C boiler, they come with their own set of issues. Changing out an old iron boiler that's connected to even older pipes and radiators, is not a "bolt in" job.

Mike T., Swampeast MO

As Steve said, a condensing/modulating boiler will thrive driving an original gravity system with standing iron rads. With an 80,000 btu/hr loss your 14 cast iron radiators will almost certainly be vastly oversized by modern standards. Such is the good oversizing as the emitters are oversized relative to the boiler.

That said, your baseboard areas might present a problem.

Do you have a single zone (thermostat) or are the baseboard areas on their own zones (thermostats)?

If you have a single thermostat and you're presently satisfied with heat balance through the house then I'll say that you'll be exceptionally pleased with the economy, comfort and versatility of the Buderus GB 142 using the RC-10 control. That said, my gut advice is to avoid any boiler using an aluminum heat exchanger in an old iron system. I would prefer a stainless steel heat exchanger.

Bruce_20

Thank you, Steve and Mike. Steve--can you recommend a unit with a steel heat exchanger that I could look into?

As to zones--we have two zones. Downstairs, there is an 8' length of cast iron baseboard on what I'll call the "main" zone (almost the whole house). Upstairs, one bedroom has a 20' length of copper baseboard, which is piped under a wall into an 10' length in a second bedroom. The second bedroom also has a column rad. (which runs on the main zone). The copper baseboard runs as a separate zone. All of the baseboard was added as a consequence of some construction in the 1970's.

I was actually thinking of pulling the bedroom rad. and all of the copper baseboard and running cast iron baseboard instead. I would then pull the baseboard downstairs and in place install the rad. from upstairs. I could then run all of the baseboard on a single zone upstairs.

Steve Ebels_3

Not steel........stainless steel

Regular steel would turn into a pile of rust in a month or two as the condensate is corrosive. If you do some digging you'll find that about the only two options for HX material are aluminum and stainless. My personal preference is stainless but many of the guys here have had good results with aluminum also. I just feel that stainless presents fewer "issues" to deal with both at the time of installation and down the road.
That being said, I use these three brands as a good, better, best scenario; Lochinvar Knight, Prestige and Viessmann. The "entry fee" for enrollment in the M/C club goes up with each of the brands listed and if you do your homework you can see why, especially in the case of the Vitodens. It's the boiler I would use in my own home hands down. Mike has one in his place and loves it...........please don't get him started raving about it!!

Here's some links to each

http://www.viessmann.ca/web/canada/ca_publish.nsf/AttachmentsByTitle/docVitodens-Features/$FILE/Vitodens-Features.pdf


http://www.knightheatingboiler.com/knight/default.htm

http://www.triangletube.com/CondensingBoilers/Prestige
Overview.htm


Enjoy!!