New Boiler: Advice (Natural Draft, Condensing, or Keep Old One?)

Palmqvist · September 2019

Hey everyone, thanks for having me on the forums here in advance. I know there are a TON of people on here who are seasoned pros with tons of great knowledge

A little bit about me, I've been a home-owner for almost 6 years and have recently purchased a different home, therefore am learning much about this home and its HVAC system. The home's original construction year is 1954 and there was an addition (large, almost equal to the old section of the house in size) constructed onto the house in the mid 1980s. I've been mechanically inclined my entire life and have worked on cars, built my parents' home with my dad and in general I'm good at electrical, mechanical, automotive, and even furnaces and garage heaters.

This house I've recently purchased (~2900 cumulative SqFt) has a VERY, very old Slant/Fin hydronic gas-fired boiler system installed in the basement, piped to the entirety of the house (not the attached garage). I contacted Slant/Fin and they stated the boiler's year of MFG is 1976, and it's a "Malibu" series, originally an oil-fired boiler. This thing was somehow retrofit converted to natural gas who-knows-when in the past. I paid a local HVAC company to do a basic inspection of the boiler and clean/test out the burners and combustion, and it's operating at 78% AFUE efficiency with 27 ppm CO emissions on combustion. It has a single Grundfos pump (unsure of size) circulating the entire system just upstream of the main return pipe at the boiler. The inspection stated the Grundfos pump and the expansion tank "are in like-new condition", and that the burner "operates decently".

I am really, really concerned about this thing. I would say that I have some decent DIY skill at HVAC now for forced air furnaces and garage heaters (I've installed a garage heater, wired and helped gas-plumb it), have done lots of maintenance work on my Goodman 96% 2-stage furnace at my previous house, BUT I have very very little experience with boilers at all, they're pretty foreign to me. I've been doing a TON of reading, video watching and learning and have done my best but I'm not sure what direction to take with this boiler. It's old, 44 YEARS OLD now! Will it fail on me in the middle of a Canadian winter? Winter gets down to -35/-40 degrees Celsius here (-37 F). Will this thing crap out on me in the middle of winter and destroy my pipes and the entire house?

What would you pros recommend? I had a quote from a local shop who had worked on this boiler for the former owner. He 'roughly' quoted me $ CAD ($ US) for a DIRECT-fit natural-draft replacement for a boiler installed, and $ CAD ($ US) for a condensing boiler installed. Could I buy a "similar" modern natural-draft Slant/Fin and install it myself? I have done plumbing with black iron, I'm VERY skilled at electrical and junction boxes/working with BX cable, etc, and have decent experience with HVAC like I wrote. I know I've read posts where you guys caution against a DIY guy doing this himself but I can't afford these INSANE quotes like this, not right now. I figure that I can buy a new boiler for approx $ CAD ($ US). Could I install it and then have a certified TSSA/journeyman come and properly connect the flue to the chimney, setup the gas burner, do tests of the boiler, all the loose-ends and sign off on my work? I feel like that's reasonable.

Thoughts??? Thank you guys in advance. Please help me before the winter hits. I'm unsure about this ancient Slant/Fin.

STEVEusaPA · September 2019

Rules of this site state no pricing is allowed.
First of all, the quoted prices aren't 'INSANE'. They are fair and what a competent professional would charge (actually they may seem a little low-ish).
A professional who has taken the time (years/decades) to acquire the proper skills, tools & techniques. Who built a business and has expenses-tools, parts, a number of types of insurance, vehicle(s) with all their expenses, taxes, employees, payroll...you get the gist.
Can you do it yourself, sure, depending on how much you are allowed to legally do.
But it can go dangerously wrong, could end up costing you more money to fix it, or worse.
If you've been reading up as you say you have, and had people come out and tell you it's working fine...then there is problems.
Your flue pipe is dangerously wrong, specifically the barometric damper (type, how it's attached) and the reduction in flue pipe size from boiler to chimney.
A total repipe using modern, recommended piping practices and modern components would be the best. Plus a mod-con will require venting thru the wall, and either option requires checking gas pressure and setting up the equipment with a combustion analyzer.

You get a person to do this as a side job. They probably can't legally 'sign off' of this, especially if you are pulling a permit.
No real warranty on the boiler, parts or labor.
You may save, or it may cost more-in more ways than money.

Jamie Hall · September 2019

A minor comment -- would you edit your post to remove the prices? We don't ever talk price here on the Wall, except in the most general terms!

That said... yeah, that's an old boiler -- and the CO measurement is really scary.

But the very first thing to do is to calculate the design heat loss of the house. This is something you can do. Slant/Fin has a very nice calculator on the web for just that purpose. Once you have that, you can begin to think about what boiler might work. Slant/Fin's calculator can also help you decide whether you have enough radiation in the structure.

So that's the place to start.

Erin Holohan Haskell · September 2019

I've removed the prices. Thanks, guys.

And welcome to Heating Help, @Palmqvist. Here are some tips for using the forum: https://heatinghelp.com/forum-user-manual

JakeCK · September 2019

Bit of advice since you are on a budget, get a working CO detector on every floor of the house.

HVACNUT · September 2019

If it were mine and I didn't convert to oil (which I probably would), I'd be looking at the Energy Kinetics System 2000 EK-1 Gas Frontier or a cast iron 3 pass boiler like Buderus, Trio, QHT, and others, a Carlin EZ Gas conversion burner, with an indirect water heater and outdoor reset.
I'd sacrifice some efficiency for reliability over a mod con any day.

Palmqvist · September 2019

Thanks for the feedback everyone. Sorry, I didn't realize those were the forum rules (no comments regarding SPECIFIC pricing of parts/materials/labour whatsoever). Does this apply directly to both ORIGINAL posts, and subsequent comments? Clarification would be good there. This being the case, I won't post any further specific prices on parts/materials/labour of a job I'm doing.

Anyway thanks. I'm not diminishing whatsoever the value nor skill/experience of having a professional with years of experience, insurance, correct tools/materials/business/employees at their disposal but I am DIY guy through and through and that's how my family has always been and how I've grown up my entire life. I'm not opposed to hiring and involving the professional gasfitter/plumber/installer, rather I am saying that I do want to perform SOME of the work. I'm all for integrating the professional HVAC guy in the job to some degree.

I always thought that ppm CO emissions about the boiler were acceptable within a limit of <45 ppm, that's what some youtubers and other HVAC professionals have indicated online in the past. This is scary that you guys think the CO emissions number is on the scary side.

*sigh*

I wasn't trying to insult the value of the quote from the company necessarily, but I can't afford it, not even close right now. I have a baby on the way in a couple months and am between houses and have alot of other looming debt at the moment. I simply don't have the funds to hire this job out completely. The only logical course of action for me is to try to do some of the replacement work myself.

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STEVEusaPA said:

If you've been reading up as you say you have, and had people come out and tell you it's working fine...then there is problems.
Your flue pipe is dangerously wrong, specifically the barometric damper (type, how it's attached) and the reduction in flue pipe size from boiler to chimney.
A total repipe using modern, recommended piping practices and modern components would be the best. Plus a mod-con will require venting thru the wall, and either option requires checking gas pressure and setting up the equipment with a combustion analyzer.

Would you mind specifically outlining for me why the flue piping is so dangerous? Is it because it has a fairly long horizontal run and it's natural draft vs induced/mechanical draft? Also I'm not too familiar with the barometric damper, could you explain abit more about it and how it works (or how it SHOULD work?). Do you believe this flue pipe is some cheap grade inappropriate stuff, or is it double-walled stainless? I used double-walled B-Vent when I did my garage heater, but then again that's a power-vented draft system, and I vented horizontally out the wall........
Thanks!!! I'd really like to learn more here.

I won't post pricing on what I paid with the professional HVAC inspection but I AM going to copy/paste here the entire inspection report for any of your feedback guys. This blows my mind that in fact, the report didn't correlate with what you guys called "safe". I'm disagreeing with you, rather I'm saying this surprises me because I DID pay good money for this inspection, above the board, registered, and with a professional company. The inspection report is as follows:

"DESCRIPTION OF WORK: Full boiler inspection on 30+ year old system. The boiler is operating at 78% efficiency with a co level of 27 ppm’s Which is a normal level. The chimney is in good condition and looks to have been recently lined. Auto bleeder on boiler is corroded and needs replacement. A section of pipe below the circ pump shows signs of leaking around the threads and also needs attention. The burner is in decent condition and burns smoothly after the air intake was cleaned out. Boiler circ pump and expansion tank are both in like new condition.
Recommendations: recommending an equipment upgrade in the future to increase heating efficiency and to ensure many
more years of safe reliable and comfortable home heating.

TASK - BG24500. Description: Tune Up Unit - Perform Professional Cleaning, Adjustment & Thorough Safety Check - Best"

I'm aware of the corroded auto-air vent (bleeder?) on top of the boiler, and I'm aware of the corroded/rusted section of pipe downstream of the boiler. I've already gone and bought a new Maid-O-The-Mist auto-air vent as well as 1 1/2" black iron fittings (elbow, reducer coupling, Tee), new purge valve and nipples for this repair job. In 2 weeks when I'm free I plan to do this work to it, unbolt the Grundfos pump and unthread the pipe from there, rebuilding from the boiler back towards the pump. Let me know if that seems reasonable. I also bought some Master's Pipe Dope for this job, my buddy (ex-plumber) said that's stuff his company used to use and it's good quality. This is some thick pipe! I've never worked with 1 1/2" black iron before, mainly smaller OD gas pipe.

Would be all for hearing further thoughts or comments from anyone. Thanks folks.

Steamhead · September 2019

What burner is on that Malibu?

Palmqvist · September 2019

I'm aware of the corroded auto-air vent (bleeder?) on top of the boiler, and I'm aware of the corroded/rusted section of pipe downstream of the boiler. I've already gone and bought a new Maid-O-The-Mist auto-air vent as well as 1 1/2" black iron fittings (elbow, reducer coupling, Tee), new purge valve and nipples for this repair job. In 2 weeks when I'm free I plan to do this work to it, unbolt the Grundfos pump and unthread the pipe from there, rebuilding from the boiler back towards the pump. Let me know if that seems reasonable. I also bought some Master's Pipe Dope for this job, my buddy (ex-plumber) said that's stuff his company used to use and it's good quality. This is some thick pipe! I've never worked with 1 1/2" black iron before, mainly smaller OD gas pipe.

Was hoping that a modern Slant/Fin or Weil-McClain natural-draft would be a "direct replacement" with minimal retrofitting. Anyone agree or disagree with that?

Would be all for hearing further thoughts or comments from anyone. Thanks folks. Sorry about the long posts but this is detailed business.

Steamhead said:
What burner is on that Malibu?

Hey Steamhead! Thanks for your reply

i truthfully have no idea, I'm not in town there at the moment and won't be back at the house for around 10 days (out of town for work right now). I can definitely have a look at the burner and take some detailed pictures of the specifics of it, placard on it etc, when I'm back next. Anything you can teach me or advice you can send my way?

HVACNUT · September 2019

An almost direct swap out to another Slant/Fin or a Weil McLain isn't exactly an upgrade. Just paint the jacket on the existing boiler. There, brand new. And count on a stainless steel chimney liner regardless of which boiler is installed.

mikeg2015 · September 2019

Might be a good opportunity to go with a condensing boiler or a combi with outdoor reset. Add in an indirect tank for efficient hot water. Can Use the chimney for single pipe venting with PVC and avoid reclining it.

Palmqvist · September 2019

HVACNUT said:
An almost direct swap out to another Slant/Fin or a Weil McLain isn't exactly an upgrade. Just paint the jacket on the existing boiler. There, brand new. And count on a stainless steel chimney liner regardless of which boiler is installed.

Not challenging you at all here but I'm seeking clarification on this. How is this not an upgrade?

My Old Slant/Fin:

-44 years old
-78% efficiency or maybe worse than what the HVAC tech says
-no idea on the condition or integrity of the cast iron inside (who knows when it's going to perforate and start leaking)
-was retrofitted unknown # of years ago to gas, no idea on the true quality of this burner they installed

A New Slant/Fin or Weil-McClain

-MAX of 86% efficiency with natural-draft from my understanding, so way more efficient
-NEW, therefore the cast iron isn't compromised or leaking
-will include a new circulator pump, bonus at least
-more build-in safeguards in place from my understanding
-NOT 44 years old!!!!!!
-included burners are probably a quality brand of burner (yes?)

Change my mind here!!!! All I'm asking is more clarification on why you don't think this is an upgrade at all.........

Also, "the chimney looks to be recently lined", according to recent inspection. So hopefully it wouldn't need to be LINED again soon. That's good yes?

Jamie Hall · September 2019

It is an upgrade, and a very significant one. I think what some might have been thinking is that it isn't really "state of the art" -- which is the modulating and condensing boilers.

That said, there are some of us who actually prefer the less complex boilers -- less maintenance, possibly longer life, less capital cost.

JakeCK · September 2019

I would replace with a new CI, but professionally installed. At 44 years its already almost half a century old and it looks as if its had a rough life. I'm looking at all that staining below the thimble and cleanout too. Got to ask how much of that made its way into the heat exchanger?

John Mills_5 · September 2019

Remember that measured efficiency is steady state or combustion efficiency. That's after the burner & boiler are warmed up and at their most efficient. If you count the heat that's pouring up the chimney as it warms up, and the heat that's pouring up during cool down after a burn cycle, it's probably 55 to 60%. That would be to compare to the AFUE of the new boilers which are 80-85 for cast iron and 85-95 for condensing depends upon water temp.

salio · September 2019

As a self-employed and licensed, insured, but most of all professional tradesman for 30 years, (woodworker / finish carpenter), and one who was doing the work long before that, I have some sympathy with the OP's desire to do some of the work himself as well as his questions about cost.
The HVAC trades have some ingredients which are a bit unique to the building trades: 1) The markup on materials. Going back 25 or more years ago, professional carpenters received the same courtesy, but it was never the same as in your industry, and now it's almost non-existent. 2) The demand for service work, which doesn't apply to all other trades, as well as the rates for it, which seem to remain robust. 3) The urgent and sometimes emergency nature of some of your work.
All of these things combined put this trade into a much more profitable level than many others. I'm not complaining or saying it shouldn't be this way. You did your homework, you paid your dues, you have trucks to buy and maintain if you have a fleet, you have employee costs, insurances, and a good amount of other overhead. But other tradesmen have much of the same investment of time, tools, insurance, vehicles, school-of-hard knocks, etc. Does anyone here know what a double-wedged and splayed scarf joint is - then have the tools, the experience, the skill, and the vision to make it? or how to design and build exterior millwork that will hold up to the elements for many decades, and again, have the tools, experience, skill and vision to pull it off. And wait, there's a schedule and a budget!
This isn't a rant, just as a balancing perspective and some sympathy for the OP who is trying to do as much work as he can himself legally and safely, to upgrade his boiler. That's all.

New Boiler: Advice (Natural Draft, Condensing, or Keep Old One?)

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