Boiler change ?

Richard_102012

I would like your opinion on my plumber suggestion. I'm from Québec, Canada and i have two Viessmann gaz boiler. One is a Vitogas 050 Cast Iron Atmospheric Gaz-Fired Hot water boiler series ECD and the other one is an old Viessmann Atola model AR145, year 1989.Those ones are used for hot water radiator heating system and the domestic water is produce with electric water heater. My plumber told me the old one is about 75 % efficient and the newer one is about 84 % efficiency. His proposal, to get better efficiency and saving on gaz bills, is to replace both of them with two Eco-King combi 140 for heating purposes and domestic water. Thank you very much for your opinion

Hot_water_fan

How much gas do you use per year?

pecmsg

The combustion analysis will give you the actual #’s. Did he do one?

SuperTech

Tell us more about your system.  What type of heat emitters? Baseboard? Radiators? Radiant flooring? For baseboard and radiators I would stick with cast iron boilers and keep your current boilers going as long as possible.  Witn modulating condensing boilers high efficiency is only seen when the return water temperature is low, lower than 130 degrees if I remember correctly.  For anything other than radiant heating I think cast iron is a much better option. 

leonz

Bon Jour Richard,

Nine percent difference in efficiency in boilers is not much unless your talking power loss of 9 megawatts
from either a 34,500 volt coal fired steam turbine or a 115,000 volt 3 phase coal fired steam turbine.

Are these boilers used in steam heating or hydronic heating?

You have 2 existing operating boilers that I will assume are fully depreciated and are at scrap value BUT do not leak and heat your building. You have a separate hot water heater that still makes plenty of hot water
is cleaned annually and does not leak.

If the boilers have been maintained by cleaning boiler properly every year and inspected by the local plumbing inspector/fire marshal annually I would not worry too much.
I have seen boiler inspectors down here just bang on the exposed steel to see how it sounds and then pass it.

Are they plumbed in series or parallel?
When were the blow off valves replaced last?
Are the gauges still functioning?
DO you have low water cut off devices installed and wired in series pairs to shut the boiler off in the event of a water loss?
Have the boilers ever been drained and the mud washed out of them?
how often is the boiler water tested if it is a steam heating system?

If you install 2 boilers the entire cost of the 2 new boilers would be depreciated over ten years using straight line depreciation expense and that could or would be a substantial expense against your gross income.

Each new boiler would have a domestic hot water coil or a circulator heating an indirect thermal storage tank used for supplying domestic hot water.

I guess you would have to use a decision tree to make the first decision and a reverse decision tree to see if it was the right one before you go to borrow money to replace them.

If you have the installed costs and maintenance and expense records for these boiler's be sure to use those total costs in the decision trees but in separate branches.

Robert_25

Richard_102012 said:

I would like your opinion on my plumber suggestion. I'm from Québec, Canada and i have two Viessmann gaz boiler. One is a Vitogas 050 Cast Iron Atmospheric Gaz-Fired Hot water boiler series ECD and the other one is an old Viessmann Atola model AR145, year 1989.Those ones are used for hot water radiator heating system and the domestic water is produce with electric water heater. My plumber told me the old one is about 75 % efficient and the newer one is about 84 % efficiency. His proposal, to get better efficiency and saving on gaz bills, is to replace both of them with two Eco-King combi 140 for heating purposes and domestic water. Thank you very much for your opinion

What is your current pricing for Gaz and electric?

Is this for an apartment building?

Richard_102012

Thanks for your answers guys. Last year, my consumption of gas was 3070 m3 for the old Viessmann Atola AR145 who served to heat my apartment with hot water radiator

Hot_water_fan

Thanks for your answers guys. Last year, my consumption of gas was 3070 m3 for the old Viessmann Atola AR145 who served to heat my apartment with hot water radiator

That's low usage - probably not worth the switch.

JUGHNE

Is that 3070 cubic meters.....not 3070 cubic feet?

Richard_102012

Yes, it's cubic meters.

The Steam Whisperer

That's about 1,100 therms

Richard_102012

The Steam Whisperer said:

That's about 1,100 therms

Thank you for your answer but I need more explanation because I'm a beginner in this subject. What's 1,100 therms means.
Richard

Zman

A therm is 100,000 BTU’s. Depending on your local gas prices, it probably only works out to $1,000-$1,500 annually. I wonder if you lost track of a decimal?

The Steam Whisperer

I just googled btu/cubic meter of gas and ended up right about 36,000 btu/cu ft

Richard_102012

What is your current pricing for Gaz and electric?

Is this for an apartment building?

Yes, it's an apartment building. A KW/H cost 0,06319 $ canadian and the gaz cost 1,70 $ canadian for a cubic meter

Zman

At those rates, natural gas would be almost 3x as expensive as electricity.

I suspect your utility is measuring in cubic meters but billing by the therm. If that is the case, the cost of gas and electricity are about the same and I would not change a thing unless something is broken. Saving a couple of hundred bucks a year will not give you much of an ROI.

Hot_water_fan

I think a picture of your bill would clear up a lot. Either way, a combi won’t do much for you.