Suggested hydronic gas boiler ~90,000 BTU Output

Steve Garson_2

I live in Denver and we have a WM GV-4 boiler. We're adding a room to the house and the boiler will need to be replaced to support the added heat load.

Suggestions from pros on what brands/models I should consider? Weather here varies dramatically during the winter, from zero degrees to 30 degree nights while days can be sunny and 50. We'll have five zones plus the indirect HW zone. Today, the single circulator of the boiler handles all the zones.

Thanks for your input! I suspect this is a bit like religion, with lots of opinions. Please share them!

Steve

Big Ed_4

Did you do a heat loss calculation ?

Steve Garson_2

not yet, since the addition isn’t designed yet.  But the contractor I end up hiring sure will.

DJD775

Was your current boiler properly sized for the house? Most times the original boiler was already over sized and will handle the additional heat load. You can download the Slant Fin app to perform a load calc on your house to see where you currently stand.
From hanging around the forum long enough most pros are going to tell you that the the installer is more important than the brand name.

Hot_water_fan

Do you need a new boiler? It’s likely the old one was well oversized. Even if the addition’s heat load calculation was high enough to justify a new boiler, I’d live with it a year to be sure. Those calculations can be easily botched, especially if it’s performed by the addition contractor.

hot_rod

What type of heat emitters?

EBEBRATT-Ed

@Steve Garson_2

I would download the slant fin app and do the house and the addition before you decide.

As far as boilers go there is probably a 50/50 split here between Mod Con high efficiency boilers and cast iron boilers with plenty of reasons for both.

Viessmann is considered top of the line for mod cons and a lot of people like HTP products.

Peerless and Weil McLain are the most popular for cast iron and there is also EK boiler which are very good if you have a good EK dealer in your area

JUGHNE

If you have a GV-4, that is 105,000 input--92,000 output---IBR of 80,000 btuh.
That GV-4 is rated at 87.3% seasonal efficiency. A mod con will not do much better if you have baseboard heaters.
That is a pretty durable long lasting boiler if maintained.

I had the exact same boiler in my house (still in the basement, BTW) in North Nebraska, it was too large for my 2380 sq ft first floor with heated basement. Colder than you, right now it is 3 degrees. Expecting -5 to -10 overnight this week.

I down sized to a Mod con that is 80,000 btu input, still a little oversized.
I had to redo some piping and got contractor home use discount so went that route.
I would have about $1000.00 (retail) in repairs in it if I were not in the business.

EBEBRATT-Ed

@JUGHNE said "I would have about $1000.00 (retail) in repairs in it if I were not in the business."

That's the sad part of the mod cons. I just don't think fuel savings can overcome the cost of repairs

Steve Garson_2

I did the heat loss calculations.  It looks like my boiler will handle the addition.  Thanks for all the suggestions.

hot_rod

EBEBRATT-Ed said:

@JUGHNE said "I would have about $1000.00 (retail) in repairs in it if I were not in the business."

That's the sad part of the mod cons. I just don't think fuel savings can overcome the cost of repairs

Assuming they need repairs?

I've owned 5 mod cons, 4 Lochinvars, 1 Laars/Baxi with nothing more than gaskets and a couple flame rods for maintenance. Going back almost 20 years now.

Many fail due to install mistakes pumping and piping, bad water quality, improper venting recirculating exhaust gases, etc. At least from the 20 year history of problems we see here.

What we don't see here at HH is the millions that run fine, some, like mine without yearly maintenance.

I expect the electronics used on new cast iron will have identical issues, if in fact that is a weak link.