Boiler Heating System Question

We bought our house a few years ago with a boiler heating system, completely new to me. The house is a 94′ and everything is original. We recently started have problems with the igniter and pressure tank, the boiler tripped a couple times after the new igniter was installed, sounds like we currently have air bubbles in the lines due to the pressure tank. We also run well water which I’ve heard is harder on boiler systems.

Couple questions:
* How long should a boiler last? We have a 94′ Weil McLain boiler, around 100,000 BTUs
* The HVAC guy is suggesting we replace the whole system: Boiler, Domestic Hot Water Tank, Pressure Tank… The whole 9 yards for around $8k. Is this a reasonable price? Would you suggest replacing the whole system which is reaching 25 years of age?

Thanks in advance for any insight.

I have owned four houses with hot water boilers. In the two houses with older boiler I replaced them both one with 95% condensing boiler and the other with a 85% Slant Fin boiler. The Slant Fin is very similar to your McLain.

It sound like you have some install issues with your current boiler.
Corner cutting on the original install.

You should never have any gurgling sounds. Does you system have pressure regulated automatic water make-up? Does you system have a “air scoop”? Is your expansion tank about a foot in diameter and a foot tall? Do you have multi-zone heating?

I love hot water heat. I had my current home built with heat in the floor/hot water heat.

$8k is a little steep. I would get some more estimates. If you can sweet pipes and have some mechanical skills. A new 95% efficient boiler is about $2700 and it takes about $1200 in additional materials to replace the complete system.

I usually do my heating work in the summer time.

djshannon wrote:

It sound like you have some install issues with your current boiler.
Corner cutting on the original install.

You should never have any gurgling sounds. Does you system have pressure regulated automatic water make-up? Does you system have a “air scoop”? Is your expansion tank about a foot in diameter and a foot tall? Do you have multi-zone heating?

We never had issues until the igniter went out. The ‘exhaust’ in the back of the boiler spit a lot of water, he said the pressure was low and the expansion tank was failing. Since then, we’ve heard the gurgling sounds upstairs and we have no heat downstairs, again he said the expansion tank failing caused these issues.

We have multi-zone heating (4 zones), the expansion tank is approximately the size you described. I’m not sure what the pressure regulated automatic water make-up or air scoop is you are referencing.

We have come to love the boiler and multi-zone heating system. We have a much larger home and our energy bill is significantly less each month.

My last house had a boiler and I don’t know much about the mechanics of them but I wouldn’t call a 94 too old. Ours was from the 60’s and it was still running in 2018. We had the boiler serviced and I asked the serviceman about it and he said “yeah its old as hell but they actually still make this same model boiler”. My understanding of boilers is that’s one of the advantages is that they last much longer than a furnace. BTW we had air bubbles in our lines before too. The serviceman had to bleed the lines to get it out. Took him about 40 minutes and he was able to restore full pressure in the system. Didn’t seem that difficult of a job and it didn’t cost us much to get the air out of the lines.

Sounds to me like your expansion tank is full of water . Most systems have some sort of air separator that will direct the air in a system to the expansion tank . I’m assuming the “exhaust “ you are referring to is the relief valve . If the expansion tank is full of water , there is no place for expansion when the water is heated , if the system exceeds the relief valve setting it will open . Then the feedwater valve will open to refill the system to the preset psi , but also introduces air into the system . I’d start with the expansion tank . The igniter would have nothing to due with the water side of the system

I install boilers for a living, If you have a diagram style expansion tank there will be a schrader valve on the tank to adjust the air pressure. If you push the valve and water comes out your tank has failed. No need to replace a cast iron boiler unless it is beyond repair. Your HVAC company should do a combustion test on the boiler and if it is running good you could get another 20 years out of it. If not, most of the time a good cleaning is all that is needed. Installing a high efficient boiler that only heats high temp emitters (radiators/baseboard) is a not necessary. A boiler becomes high efficient by condensing the flue gases to extract the extra 15%. If your return water temp is consistently above 135 degrees the boiler will not condense and is effectively a 80-85% boiler. There are some other advantages such as modulation rate and outdoor reset control but most of the time it doesn’t justify the added cost. The ignitor issue is completely unrelated to the water issues as was said above. A good purge/bleed and a new expansion tank should be all you need. Adding an air eliminator (air scoop) will help you remove air automatically.

I thank everyone for all the input. How do you know when a boiler and/or Domestic Water Tank needs replacing?

On top of the issues I’ve mentioned above, we have some minimal water leaks around the boiler and water tank. Not sure if this is due to the expansion tank failer or not.

Sounds like most of you recommend just replacing the expansion tank and bleed the lines, we were leaning towards replacing the whole system but are now second guessing.

Appreciate everyone’s input.