Residential boiler replacement

[Enigma]

Ughh, looks like we probably have to replace our early 1980's "Superhot" boiler for our home heating system. It's a baseboard system, two zone, roughly 1500 square feet total. I did replace the electric hot water tank in 2005 with a gas fired tankless Rinnai, it's worked flawlessly since.

They guys we use for annual maintenance, Somerville & Sons, are alright but I'd like to hear from some other sources on perhaps seeing if it is indeed repairable and getting some quotes for a new installation.
Apparently the heat exchanger has/is packing it in, leaking CO2, refractory failing, etc etc, it does have various new parts from recent maintenance; new pump etc etc.

Can anyone suggest some good local companies?

 

[Glenn-BJ74]

I put the high efficiency condensing Navien (Korean) in the shop. - 15 years warrantee on the heat exchange


Navien NHB Condensing Boilers

 

[GTSSportCoupe]

I went to an electric boiler from an oil boiler about 7 years ago now. Might have considered natural gas if it was in our neighborhood. We have hydronic heating with base board registers; three zones in about a 2400sqft house. It's a 24kW unit (needs a 125A breaker). Lucky for me the builder of our house (30 years ago) was thinking ahead and had pulled said circuit to the furnace room already. It has been excellent; no hassle or maintenance with simple electrical heating elements. Costs about $750-1000 to heat the house through our mild west coast winter; would probably be much cheaper if I had newer windows/doors. Here is the unit we ended up with: Argo Electric Boiler AT244610C I definitely recommend it.

 

[Glenn-BJ74]

Gas is a 1/3 rd the cost of electricity's high trailing block rate (compare after tax/fees marginal rate).
Kelowna Fortis is 13.6 cents per kWh x 293 kW.h/ GJ = $39.85/GJ.
Kelowna Fortis natural gas $11.55/GJ.

Your gas rates vary regionally - check your last bill.
Yesterday we got rid of our Kenmore electric range and installed a new Samsung gas range.

 

[AJAEbj42]

^ Like I've said before, I always appreciate an economist's analysis...

We've switched to hot-water on demand with our renovation for cost savings.

Thanks Glenn!

 

[Enigma]

The electric option is interesting, but since the existing boiler is gas all the infrastructure is already in place. I also don't have the capacity in my breaker box (which is in the same room though) I don't think.
Quotes should be rolling in the next few days. At this point it looks like we'll just be replacing with a newer version of the Superhot (locally made and good simple boilers). I'd love to swap it out with a Rinnai wall mounted boiler for the room saving, but the high efficiency units are a huge dollar difference (at least twice the price and more), and there is no significant cost savings benefit for our house with base boards to go with the high efficiency.

@AJAEbj42 , out of curiosity, what on demand system do you now have?

 

[Glenn-BJ74]

Jeff send me your GJs per year consumption your average gas costs (after tax) and the two boiler capital costs and their efficiency ratings and I can do a payback analysis for you, but FIRST check with your gas utility to see if they offer rebates on qualifying boilers, which may pay for the difference between standard and high efficiency (condensing) boiler.

PS - We need to save money to sensibly redeploy on Cruisers

 

[Enigma]

Sure, will do thanks.

 

[Glenn-BJ74]

Hells Canyon departure Saturday at 7:00 am.

 

[Enigma]

Only two quotes in so far and no cost breakdown (I've replied back and asked for it). One at $5706 and another at 4700 installed with a new Super Hot MG50 , 85% AFUE. Rough guestimate at this point that the seperate cost of that boiler is about $3000.

A Rinnai E75C based on the Amazon.ca price of $4144 and an AFUE of 96.5%

Total GJ used from Jan 2014 to Dec 2014 was 96.6, jan 2015 to present 60.2

Never really looked closely at the billing breakdown; Gas cost from most recent bill:

delivery @ 3.559 per GJ
storage @ 1.334 per GJ
cost of gas @ 2.486 per GJ
carbon tax @ 1.4898 per GJ

all that adds up to a bill of $33.55 for 2.1 GJ

I'll update when I can get some better numbers. Hope that makes sense, doesn't to me

 

[Glenn-BJ74]

What is your current boiler efficiency?

Is the gas boiler your only gas load?

 

[Enigma]

No idea what the current one is, it's an early 1980s Super Hot 90 model=not very good. The only other gas load is the Rinnai tankless water heater.

Quotes are slowly rolling, and whomever wins will first be tasked to see if the heat exchanger et all can be cleaned/repaired and just get it running for a little while longer if possible. ~$700 vs $5000

 

[Glenn-BJ74]

Condensing boilers have a second heat exchanger, which scavenges heat from otherwise wasted flue gases - this technology has increased thermal efficiency from roughly 80-85% to 96-98%.
Here is an example based on the rough numbers you dug up for the high-efficiency versus standard efficiency boiler decision. If you get better numbers you can revise.

Assumptions
Annual consumption = 96.6 GJ (this all boiler load?)
Current efficiency = 80% estimated
Net Load = 77.3 GJ
Natural gas cost = $33.55/2.1 GJ ~$16.00 GJ
Annual cost = $1,550.00 (should be after tax)

Condensing Boiler
Boiler life= 20 years
Efficiency = 96.5%
Incremental capital = $1,144 (high-efficiency over standard)
Estimated new annual consumption = 80.1 GJ
Reduction in consumption = 16.5 GJ
Value of reduction in consumption = $264.00/yr.

Economic Return
Gross savings over boiler life (20 yr)= $5,300.00.
Net savings over boiler life = $4,156.00 (less incremental capital cost)
Payback = 4.3 years (1,144/264 benefits accrue after 4.3 years).
Internal Rate of Return = 23% (over 20 yrs.)
Where can you get this?

With Utility Incentive ($500 example - you need to check)
Reduces incremental costs $1,144.00-$500=$644
Net savings over boiler life = $4,656.00
Payback = 2.4 years
Internal Rate of Return = 41%

 

[kim]

I've just been schooled!

Great stuff, Glenn!

 

[BCR4619]

Did you get anywhere with this?

I just replaced a cast iron boiler for a Weil McLain because they never had it serviced and it cracked! then the next day I replaced a cast iron boiler for a high efficiency IBC under a staircase, that was fun........

You can get away with high efficiency if you have a radiant slab as they run around 109-120 F thus getting the most out of the heat, if your running baseboard there is no point as your running around 180 F

 

[BCR4619]

Cast Iron install on the top followed by 2 of the IBC

 

[Enigma]

All done, for now anyways. Decided to just try and repair the old faithfull unit and it seems to have worked fine. The guy that repaired it had quoted to replace with a Weil Maclean unit coincidently.

 

[Enigma]

What's that inline doodad on the floor in the IBC picture?

 

[sailor]

Maybe a fluid conditioner?

 

[BCR4619]

Its an acid neutralizer as the condensate from the flue products is very acidic and will pretty much eat trough ABS and various other piping except PVC.

Basically has lime in there, but it's amazing how much liquid they produce at lower temperatures where they run at a high efficiency.

You can't really tell but the IBC when it's running (or any high efficiency boiler for that matter) they look like a mini steam generator outside, you can leave you hand over it and it's just warm and won't burn you.