Indirect Upgrade with new boiler

Runswithlight

First and foremost looking to install a 50gal Lochinvar indirect to replace my stand alone tank. Have a lot of simultaneous HW needs and the continuous draw meets my needs. Knowing the requirements for recovery speed (being TOP priority) is 133k min via 1in pipe with 14g/min flowrate leads me to my next challenge.

At the same time, I am also OK with replacing my existing boiler. Currently have a 1970s American Standard CI boiler with 96k output. Current heating needs for 2 zones of cast iron baseboard (currently installed) is about 70k. Looking to also add a 3rd zone (another 15k) to keep that garage warm as required, making the total load around 90k before the indirect.

Best case, I replace the boiler with a slightly oversized mod-con (150/155k) - either Lochinvar Knight or WM Eco-Tec 150k. Everything is high temp, no radiant zones, so know that saving aren't coming from there. Ideally want to move the entire setup against the wall and direct vent outside, saving a ton of room in my combo laundry / boiler room.

I've had several companies push back and say I should just go CI get a CGi-6. The cost (including repiping, manifolds, etc) is pretty much the same. I have no issues with having proper maint done on the HE models. Am I missing something that should dissuade me from going the mod-con option? I feel like being able to push 100% for DHW and mod down for my heating needs is a win win.

tcassano87

I think you’re going to get a lot of different opinions. Me personally although I understand wanting to create more space, I always prefer a cast iron boiler, with an in direct or seperate water heater. In my experience so many less issues overall. I would use a Burnham Alta if I were too install one in my house though

hot_rod

With a 70K load, no reason to go any larger than a 120,000 or so mod con. That gives you plenty of DHW and can be limited to the 70K for heating.

1" piping on the indirect is plenty for 70- 100K boiler input.

Lochinvar Knight is one of my favs.

HVACNUT

There is no 90K before the indirect. Its just 90K. If you're looking for steady DHW and quick recovery with 90K output, look at a reverse indirect like the Turbomax 23. If your heart is set on the Lochinvar, set tank temperature to 160°, with a thermostatic mixing valve to temper down to 120°. As far as what type of boiler? Not sure why several contractors would try to persuade you away from a mod con. Maybe they see something we don’t. Either way, you size the boiler for the heat loss, not DHW needs. Especially with priority. The only boiler thats oversized to meet DHW demand is a combi on smaller residential homes. I service houses that have 250 gallons of DHW ready to go at all times, and the boilers are sized to exceed those demands. But these are not typical circumstances.

JimP

I’m involved with a similar question. I’ve decided that the Squire indirect looks like a good bet. I favor the cast iron boiler in spite of an extremely confined space. I believe that carefully planned piping and controls will mitigate the space disadvantage.
Two questions…Wouldn’t a CGI 4 or maybe 5 be big enough? Why replace the boiler at all? If it’s reliable why not pipe it so that it can be easily replaced in the future. Be careful planning for future needs with that garage heat. If that slow to happen or doesn’t occur it’ll be frustrating. You end up with an oversized boiler.

psb75

If you have a cast iron baseboard zone you DO have a radiant heat zone—not to be confused with a "radiant floor" zone. That is better than a fin-tube b.b. zone. Wall-hung Loch. Knight boiler and ind. tank will perform well and save much floor space. Use the outdoor reset feature!

Runswithlight

https://forum.heatinghelp.com/discussion/comment/1890108#Comment_1890108

Thanks for this. Not set on anything, just trying to do it once! Turbomax looks great. Had another person here today, who had similar insight. They do a lot of larger and more complex jobs and also agreed mod-con makes sense. Seems the smaller resi guys seem to love the CI and are used to people insisting on set and forget.

Runswithlight

https://forum.heatinghelp.com/discussion/comment/1890135#Comment_1890135

Parts are not avail. One burner doesn't work, a lot of the piping around it is corroded. If going through the effort of repiping anyway, doesn't make sense to keep it. Def do not want to move the old machine!