Residential Customer Trying To Decide Between Cast Iron vs Copper Fin

Santaur

Hi there. My homes boiler broke on Friday night and we've gone the last 3 days without any hot water. My wife is starting to look at me funny.

I've gotten a couple quotes which seem reasonable, but they are offering two very different systems. I was hoping you could help give me your thoughts between the two? Here's the background on our house: we have 184 feet of baseboards that are in 3 zones. We also have a 2 bathrooms, a dishwasher, and we need to make baths for our kids. We are also at 7,000 feet altitude.

COPPER FIN VENDOR:
- Furnish & Install (1) JVS 125k btu
LAARS mini therm copper fin tube
boiler

CAST IRON BOILER:
Furnish & Install 1 Force Cast Iron Boiker 165k btu

They both make cases why I should use one or the other and I can't tell which one is better for my situation. Would you suggest cast iron or the copper fin?

Thx.

Jamie Hall

Well... first thing is to make sure that they are big enough -- but not too big. Did either of the vendors do a heat loss calculation on the house? One of the two of them is wrong -- possibly both -- since the sizes are significantly different.

So... that said, both types of boiler work very well.

Santaur

Hi Jamie. Thanks for the quick reply.

Well the cast iron vendor who has the bigger boiler said that he thought the other one was too small given the amount of baseboards and the altitude. He did a calculation where he subtracted 20% off the btu of the boilder to make sure that it was large enough for 650 x per square foot of baseboard. Is that what you mean by heat loss calculation for the house?

Once the size of the boiler is correct, is there any reason to choose one type of boiler over the other? Or do you think that both boilers will work well for our situation?

HVACNUT

Typical fin tube baseboard will deliver 600 BTU per linear foot @ 180° SWT.
Yours will get 110K BTU's.

Download the (free) Slant/Fin heat loss calculation app and you'll see what goes into proper boiler sizing.

Either of those boilers are fine. Not necessarily in size.

Has anyone checked the condition of the chimney? Exterior masonry chimney will probably need a liner if one is not already there.

What are you currently using for domestic hot water?

Jamie Hall

"Is that what you mean by heat loss calculation for the house? "

No. see @HVACNUT 's comment.

Santaur

Hi HVAC Nut. So our exterior masonry chimney is not lined.

Our current domestic hot water is an always hot (I know that's not quite the right name). Both estimates offer a 60 gallon separate tank for domestic hot water.

bburd

Everhot? A tankless water heater connected to your (broken) boiler, right?