Boiler choice

Alan (California Radiant) Forbes

So, when you go to a job and the old Laars or Hydrotherm or ARCO or whatever boiler that has lasted 20-30 years has given up the ghost, what is your go-to boiler?? We're talking high temperature - cast iron radiators.

Alan (California Radiant) Forbes

Heatloss is around 110K BTU from what I can tell.

Design day average water temperature? 170°F

hot_rod

Sounds like a nice cast iron boiler would work, if they want another 20- 30 trouble-free boiler. Something with sealed combustion for outside air.
Does it have a B-vent in good condition?

unclejohn

Triangle Tube.

SWEI

Triangle Tube as well -- primarily because of the distribution support we have.

NYplumber

Hey Alan. If i recall you have installed a few viessmann boilers. How about the new CU3A? They have one in a size close to that heat loss. Its pretty high mass and is rated for higher temps then the average mod con. It also doesnt have flow requirements. It is essentially a modern day version of a cast iron boiler.

You could always go with a standard cast iron boiler from any of the big manufacturers out there. If you choose this route, get something without proprietary controls to keep repair costs down.

Chester

Alan (California Radiant) Forbes said:

So, when you go to a job and the old Laars or Hydrotherm or ARCO or whatever boiler that has lasted 20-30 years has given up the ghost, what is your go-to boiler?? We're talking high temperature - cast iron radiators.

"high temperature cast iron radiators" --

I assume from your username you might mean 'hi temp' relative to radiant, and just wanted to point out that cast iron is effective and comfortable at pretty low water temps, making it an ideal candidate for a modcon.

I'm in the northeast and have been keeping my house toasty this winter with 100-110F supply water even down into the mid-20's. The math says I have enough radiator capacity to keep the house at 70F on my design day (4F) with boiler supply at 130F.

The question is how much EDR of radiation do you have relative to heat loss. What kind of building and how big? Older homes are typically over-radiated, especially if they've subsequently been tightened up.

Also, what's the basis for the heat loss? A 110k heat loss is more than double, maybe even triple, the heat loss of an average residence here in New England. For example, my reasonably well insulated 1,400 sq ft cape built in 1940 has a 25K Btu/hr heat loss at 4F outside temp.

CMadatMe

Alan,

Rads all getting thermostatics? How is it going to be piped? Constant circulation or zoned out?

Most important questions is where is the budget and what is the homeowners expectation for the system?

Alan (California Radiant) Forbes

You can't get cast iron boilers in California anymore. And Mo: My Viessmann wholesaler doesn't stock the CU3A yet.

Steve Minnich

I'm partial to the Lochinvar WHN. It's been a trouble-free product for me and the support, locally, is very good.

Easy control to navigate, set up to handle 3 different SWT's.

There's a couple things on it that I would like to see changed but they're minor, not game changers.

Paul48

Doesn't Viessmann top out at like 160* supply?

NYplumber

@Paul48 not on all units.

hot_rod

Stephen Minnich said:

I'm partial to the Lochinvar WHN. It's been a trouble-free product for me and the support, locally, is very good.

Easy control to navigate, set up to handle 3 different SWT's.

There's a couple things on it that I would like to see changed but they're minor, not game changers.

Copper tube an option in California? Lochinvar still offers them, Copper is still by far the best heat conductor. I'm not sure what controls are on their copper offerings.

SWEI

With all that mass of iron and water, full ODR is really helpful. By the time you add it to a copperfin, it's usually cheaper IME to just buy the mod/con. With a fire-tube, the piping is pretty much bolt up and go.

One of my few beefs with the Lochinvar WH design is that they direct-couple the intake pipe to the fan. This does not play well with leaves and dust.

Alan (California Radiant) Forbes

So, that was a general question, but I had this current job in mind. I just visited the house this afternoon in SF. I was referred by a friend and the owners and I had been communicating by text. I spent most of the time on the road. It's our first big rainstorm and traffic was miserable.

This Mighty Therm 125K BTU boiler served radiators before starting to leak. I'd go with a condensing boiler, but there's no way to get piping out of the bunker boiler room. The easiest thing to do is to install another non-condensing, atmospheric boiler and connect it up to the existing flue. I feel so cheap.

Alan (California Radiant) Forbes

By the way, check out that B & G circulator. It's not a series 100, but a HV (high volume). Can you see how the motor mount is sagging? It's toast.