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Old 11-10-2009, 05:36 PM   #1
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Replace Boiler or try to improve?


Hi guys, I'm looking for some advice on my boiler. It is a 35yr old Super Hot (CAN company) SS180 nat gas HW boiler that is running fine. I'm trying to decide if I should replace it. It does not have any glycol running through it and having only live in the house a couple of years can only say for certainty that it was serviced last winter but it appeared to have been a long time since it had last been done. Until I installed an iron filter in my water system this summer, I had water with a lot of iron in it. This seems to coat pipes and such with iron deposits more than cause additional rusting ( it may even prevent it). What tends to wear out on boilers as they age?
Is it running on borrowed time?
What approx.efficiency would this boiler have when new and now?
What kind of % efficiency can be had by installing a vent damper?

Thanks in advance for the replies. A very informative site.
Bootsnixon

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Old 11-10-2009, 06:02 PM   #2
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Replace Boiler or try to improve?


Post some pics of it. 35 yrs ago efficiency was a joke/not a valid concept as gas was cheap especially in Alberta. Probably around 50% efficient. Not possible to add a damper as that requires a set of special electric controls which cannot be retrofitted to your unit. It may develop a sudden leak at the worst time (Xmas) or go for a few yrs, you roll the dice. I would recommend a higher efficiency Weil McLain boiler (the CGi and CGa's are good value and we sell lots of them): http://www.weil-mclain.com/products/...ired%20boilers and with the 15% Fed Home Improvement Grant and some possible provincial grant you have the best time to do it NOW. The Fed one expires Jan 31. I lived in Calgary for several years (Ralph was my MLA). LOL Thought he might fill his pool with beer.


Last edited by yuri; 11-10-2009 at 06:05 PM.
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Old 11-10-2009, 06:58 PM   #3
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Replace Boiler or try to improve?


I prefer the Ultra.

There should be a BTU input, and a BTU output rating on it.
Divide them, and you have you'll output efficiency at the time of install.

Fresh water, is a killer of boilers.
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Old 11-10-2009, 07:26 PM   #4
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The Ultra, Sweet Machine, like a Lennox G71, problem is there is probably only a half dozen guys like us smart enough to fix it. Efficiency wise that is not the whole story, I believe. The newer boilers lose less air up the chimney on the off cycle and the heat transfer rate of a old boiler is a lot less with scale buildup inside.
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Old 11-10-2009, 07:41 PM   #5
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Yea. Parts changers and Ultra's don't mix to well.
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Old 11-10-2009, 07:49 PM   #6
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Quote:
Originally Posted by bootsnixon View Post
It is a 35yr old Super Hot (CAN company) SS180 nat gas HW boiler that is running fine. I'm trying to decide if I should replace it.
50% chance to reach 45 yrs with this. 80% of HVAC equip. this old has been replaced by now.
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Old 11-11-2009, 12:32 PM   #7
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Replace Boiler or try to improve?


Thanks for the replies. 180k input and 144k output so I guess they are saying the unit was 80% efficient when new. Would anyone venture a guess as to the efficiency now with it probably scaled up yet relatively clean fins and burner orifices? I'm just trying to make a guess at my payback timetable and whether it's worth doing now on credit or like a few have said, roll the bones on it lasting and save my money up to replace in a couple of years.
Thanks again,
Bootsnixon
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Old 11-11-2009, 12:48 PM   #8
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This can get REALLY complicated but I will try help you narrow it down as I see it. Read this first:http://en.wikipedia.org/wiki/Annual_...ion_efficiency

Your boiler falls into the conventional category due to its age and the design technology of the time it was built. It may in theory transfer that amount of heat when totally clean, no way to measure the scale and know now. AFUE attempts to measure the true heating cost of different types. A sealed combustion high efficiency is ALWAYS the best because NO air which is worth $$ is consumed from the house to feed the fire. In boilers they are VERY expensive and the system has very little leeway for contamination or the boiler will overheat. My very well experienced plumbers recommend the 2 I showed you as the best value for the dollar. The Ultra is GREAT but takes a LONG time to pay off the extra cost and can be costly to repair and needs VERY experienced and VERY well trained plumbers to install it, set it up etc. Great if you can "find" them.

I will give you a VERY rough idea of the cost to install yours. We did one for $7-8000 not long ago. Every year you keep yours you will pay at least 5% more the next year due to natural inflation. You probably can save at least $500 or more a yr in gas over the one you have now. Your boiler may be oversized (happened ALL the time in those days as bigger was better and gas was cheap). If you can find a very experienced heating company to do a proper heat load calculation for your house the proper size boiler will save you lots of $$.

Where you lose a LOT of energy/$$ is in the off cycle with your 6" chimney losing LOTS of heat 24 hrs a day. Quite a huge issue in Canada as you have a very strong updraft in that chimney with the basement being 70 deg F and outside -30 to 40 F. The greater the differential the stronger the draft and the more $$ up the chimney. The burners and heat exchanger are smaller/better designed these days for more efficient heat transfer and better/cleaner combustion etc.

It usually takes a least 1-2 days to drain the boiler and alter the piping, install new circ pump and bladder expansion tank. The boiler may or may not be in stock at the wholesaler. Not a process you want to go thru when it is -30 or colder.

You will qualify for some of the 15% Fed home improvement grant and call ATCO or whoever supplies your gas and the Prov govt to see if there are more rebates for upgrading in efficiency.

Last edited by yuri; 11-11-2009 at 01:04 PM.
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Old 11-11-2009, 01:04 PM   #9
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You'd think by measuring the fuel input for 60 sec. and a sample of the BTU's per minute that went up the flue, the instantaneous efficiency could be measured. This measurement would be the best attainable efficiency you can do with your old unit.

With HVAC equipment this measurement/calculation can't be that hard. . .or can it be?
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Old 11-11-2009, 01:07 PM   #10
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You need to look at the BIG picture. Combustion efficiency is ONLY one part of the equation. Cost of reheating the combustion air into the house and the heat lost up the chimney is the other huge unmeasurable factor. A 2 story house is even worse as the chimney is higher and has more drawing power/draft.

Last edited by yuri; 11-11-2009 at 01:11 PM.
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Old 11-11-2009, 01:41 PM   #11
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Quote:
Originally Posted by yuri View Post
You need to look at the BIG picture. Combustion efficiency is ONLY one part of the equation. Cost of reheating the combustion air into the house and the heat lost up the chimney is the other huge unmeasurable factor. A 2 story house is even worse as the chimney is higher and has more drawing power/draft.
If these factors haven't changed they should drop out of the calc. I would think the problem is that this test wasn't done when the unit was new.

Based on a present day measurement, what could be the max and min guesstimated efficiency when new?

Depending on the cost of this test
http://en.wikipedia.org/wiki/Expecte...ct_information
I'd do it, for this repair/replace decision. The information will not be perfect but it must be worth something.
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Old 11-11-2009, 02:00 PM   #12
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They are the big part of the equation. In the old days we had no choice but to drive big V8 gas guzzlers or use only one type of inefficient boiler/furnace which was available. Now we have a choice and can pay less. Only Einstein or Steve Jobs or Wozniak could understand all your equations. The average guy just wants to know why it is worthwhile to upgrade from a mechanical point of view/not have a dilemma later, heat is important where we are, not just saving a buck.. At least my customers do.

Last edited by yuri; 11-11-2009 at 02:06 PM.
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Old 11-11-2009, 03:59 PM   #13
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Quote:
Originally Posted by Yoyizit View Post
You'd think by measuring the fuel input for 60 sec. and a sample of the BTU's per minute that went up the flue, the instantaneous efficiency could be measured. This measurement would be the best attainable efficiency you can do with your old unit.

With HVAC equipment this measurement/calculation can't be that hard. . .or can it be?
With a boiler. You would have to know how many gallons of water are being circulated through it.
The sane as you need to know how much air is being moved through a hot air furnace.

This would tell you steady state efficiency.
But, not its AFUE.
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Old 11-11-2009, 04:03 PM   #14
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Quote:
Originally Posted by Yoyizit View Post
If these factors haven't changed they should drop out of the calc. I would think the problem is that this test wasn't done when the unit was new.
Steady State Efficiency can effect AFUE, but AFUE can't effect SSE.

So there is no simple test you can do to determine AFUE of older heaters.
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Old 11-11-2009, 04:06 PM   #15
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Boots.

If you have a load calc done on your home. You may find you don't need as big of a boiler.A new boiler, that holds less water. Will have less standby loss.
plus, uses less fuel to heat the water that just sits in your boiler after the heat call is done.

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