When to replace a hydronic heat gas boiler?

Aaron Daniel

5 months ago we moved into a 25 year old house that uses hydronic heat via baseboard radiators and a gas boiler. It seems pretty simple, with a zone for each of the 2 floors, but aside from the pump and possibly one of the expansion tanks, it looks like all items are 25 years old.

The boiler was made by Raypak (part of RayVac) in Sept. 1981. It appears to use plain water (no glycol) up to 170-180 F at the tank, and can hold our house at about a 40-45 degree F differential to the outdoors. It looks like we'll be using it 7-9 months of the year, and it's been running full time lately to try to keep up with the 10-20 degree weather.

Our home inspector felt it was probably time to replace the boiler, just based on it's age. While I agree that the separate hot water heater that appears to be just as old should be replaced, I don't have a grasp on the life expectancy of a residential boiler. How long do they last. Conversely, if it still has life in it, are new ones that much more efficient that we should have one installed in the off season next summer?

Hydronic heating is new to us. Is there some general annual maintenance that we should do or have done? The Home Depot "Home Improvement 1-2-3" book glosses over a couple things like oiling the motor (I think ours is sealed, so no oiling needed), bleeding air from the baseboard radiators (ours don't have bleeders on them, so I don't know how to get any extra air out of the system), and repairing a waterlogged expansion tank (one of ours is a newer one with a diaphragm, so this is not needed, and I think the other one is too since it looks similar but I haven't taken off the insulation to check to see if there is an air valve at the top). A search about boiler maintenance made it sound like I should drain out a couple gallons of water from the boiler to get rid of any sludge. Is this right, and is there anything else I should do...or have done?

Finally, we hear some banging coming from the garage (where the boiler is) when the system just turns on, either from having the power turned on or when the thermostats start the system. I haven't narrowed it down to see if it's just one zone or the other, but looking in the boiler closet today I see the 2 zones share the same pump and expansion tank(s), so I don't think it's zone specific. The Home Inspector noted in his report "Unit makes gurgling noises indicating a possible waterlogged or leaking expansion tank.". Does that seem likely? On the one tank that I know is an expansion tank, I took an air pressure reading today of about 22 PSI while the system was running (water at 170-180 F).

Thanks for any help, ideas, or links to general info that you can give me.

Aaron

GW

lots of thoughts

Aaron, as far as replacing, keep in mind you're asking "heating professionals" so you may get biased ideas. A heating guy will say one thing where as, let's say your finacial advisor, might say something opposite (is suzy orhman on this sight??).

I think it's nuts to consider keeping that old beast. Could you nurse it along? sure. Will you be able to find someone to fix it when it dies on a Friday evening, or next sunday morning when the heating guys of the world will be thinking about football? Unless you have a defined arrangement with a heating pro, it's like a crap shoot.

As far as the Home Depot book, it's hard for us heating dudes to keep a straight face with that question. The ideas are so bland and generic; it's not even 'real life'. I've thumbed through plumbing repair books several times just to see what's being printed, and I gotta say if you can get through a situation using one of these books, consider yourself lucky. Many problems are electrical when it comes to heating (controls). If you don't know how to use a multi-meter, fuhgettabout it... I realize you're trying to learn some concepts here, so please don't take my Sunday morning coffee answer personally.

We install boilers 12 months out of the year. It makes no difference.

The noise? Is it the boiler, or the system? Big difference. maybe the pipes are expanding and creaking against the joists? The pressure is fine, maybe a few pounds too high, but it's not a problem. It is not likely an expansion tank problem. Can you take a pic of the boiler? Us heating dudes love pictures.

Gary



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David Nadle

Make the best use of the time remaining.

As a fellow homeowner my advice to you is to use the remaining life of the boiler to find the best heating company in your area and develop a relationship with them. While they keep your old boiler in service, talk to them about eventual replacement. Develop a plan. When the day comes that replacement is a necessity you'll be ready to act right away, without scrambling to find the right people and information.

Aaron Daniel

While I'm starting to agree that it's probably getting to be time to replace it, if for nothing more than just an efficiency standpoint, there's a good chance that we will be adding onto the house. Since the current system is working, I'd rather wait up to 12 months to have a good idea if we will add on up to 50% of the size of the house, and then can get the new piping plus a properly sized boiler all at the same time.

On the HD book, I was sure it wouldn't say much in comparison to what you guys know, and it specifically says to call a pro for most things related to the hydronic heating, but it and other articles make it sound like most water hydronic systems have bleeders. I could see skipping them in a system not running water, but how common is it to not have them at all on a water based system. Better yet, since ours don't have them, do I or a pro need to get air out of the system every once in a while? If so, how should I go about it? The home inspector thought the system hadn't been tuned up over the past 6 years while the previous owners were here, and given the owners I think that's likely. I'll work on finding a pro to give it a tune up in the coming 2 weeks, but is there anything I can do in the mean time?

As for the occasional banging, like I said it seems to be only when the whole system starts up (or possibly shuts down). It's not when the boiler fires up, and the noise seems to come from the boiler closet. It really hasn't bugged us much lately, as yesterday was the first day that it got a couple degrees above freezing in a few weeks. Between the 2 zones, I think the system has kept going pretty much the whole time, and so I think the only time we heard the banging in the last month was when the power went out (system going down and/or coming back up).

I'll add a couple pictures once it stops snowing and I can get the car out from that side of the garage.

Aaron