Residential boiler questions


Old 01-21-19, 11:45 AM
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Residential boiler questions

Hello...I just started looking into some issues with our boiler and I have some general clarification questions first to make sure I'm making correct sense out of our existing system. I thought I took a decent pic of the overall layout behind the boiler but turns out I didn't, so there's pictures of the different sections.

In the pic with the expansion tank, what's the medium-sized turquoise part that's corroded down the side? The small part on top of that is a air float vent if I'm not mistaken, it also heavily corroded. The next pic shows a close-up of the far size of that vent - there's a star-shaped opening. What is that for? There used to be a small cap on top of the black stub that you can see. I was under the impression it could be turned to open/close the vent, so I tried turning it with pliers and it ended up snapping off. Oops.

Next pic - blue handle and orange bell shape thing. Blue handle seems to be to control whether new water is allowed into the system or not. Orange bell shape thing seems to be a water pressure reducer or something - I guess it knows when to let more water in based on the water pressure of the system?

next pic - drain valve.

Final pic - relief valve.

Anything off in my assessment of the system parts?

Now on to the functional questions:
I used the stickied posts in the forum to construct a pressure gauge to verify my boiler's pressure gauge. It checked out to be ok. The relief valve has been dripping water every time the boiler runs for awhile now. It started last winter and has gotten progressively "worse" - meaning it drips more frequently now than it used to. I tried to follow the stickied instructions for checking my expansion tank. I started draining water from my drain valve and the pressure dropped from 11 pounds to about 5, then slowly rose back to 11. Realized then it must have been feeding new water in so I closed down that valve with the blue handle - it was stuck tight at first, and then still fairly hard to turn once I got it unfrozen. Fairly certain i got it closed down all the way but I can't be sure. Drained more water -pressure dropped to 0, but then eventually rose back up again, albeit slower than the first time around. Would you say it's likely that new water was still coming in, either because that blue valve is shot from age, or because I didn't have it closed down tight? I checked for auto air valves on most of my baseboards and didn't see any, only manual ones, so I don't think it was letting air into the system.

When I press the valve on the bottom of the expansion tank nothing happens. No water comes out and no air pressure either. The tank feels light when I wiggle it. I put a bicycle pump on the valve and tried to add air and it wouldn't take it. Seems like the valve is completely jammed or gummed up.

Minimum work needed at this time (assumed - would like verification!):
-Replace expansion tank
-Replace air valve sitting above expansion tank
-Replace the turquoise color part sitting between the two, whatever it is?

Work I'd like to do if it's not going to be too difficult:
-Replace the drain valve - it now leaks a bit, even after being tightened back down all the way. It's not awful, but I'd prefer no leak over a small leak. It appears that it would just unscrew out and then screw a new one in, but I'd presumably have to drain the entire system first. How big of a chore is that? More importantly, how difficult to refill the bleed the system?
-Replace the corroded valve with the blue handle - that's copper assembly which I'm not familiar with.

Any serious safety concerns with doing any of the above? Or things I should be aware of that I might not think of on my own since I haven't done any boiler work before? I saw mention on some other site of breaking the "combustion chamber" - what does that mean, and would that be a concern with replacing any of the parts I've outlined?

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Last edited by PJmax; 09-07-19 at 11:51 AM. Reason: resized pictures
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Old 01-21-19, 01:17 PM
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1) That is an automatic air vent that is corroded that you broke the cap off. The cap is suppose to be loose for proper operation. If it was closed it was because the vent leaked. Needs to be replaced.

2) Orange Bell shape valve. That is an automatic feed valve that allows water to feed the boiler when needed. It is factory set at 12 PSI but is adjustable. You never want less than that in your boiler and sometimes needs more.

3) The blue valve before that is the manual shutoff in case of repairs. If water continues to feed the boiler with the valve off it is leaking by and should be replaced in case of maintenance.

4) The red drain valve. If leaking should be replaced or you could put a hose cap on it until boiler has to be drained for other work. Not an emergency.

5) The expansion tank has an air bladder in it that comes factory charged at 12 PSI. If that bladder looses its charge either by rupture or just over time it needs to be recharged or replaced. You mentioned it would not take a charge so it must be replaced.

6) Relief Valve. Most likely leaking due to excessive boiler pressure (30 PSI) when water is heated due to a defective expansion (extrol) tank which is there to accept the heated expanded water just like an overflow container in a car.

7) That Turquoise fitting housing the extrol and vent is your AIR SCOOP. Once you clean all the corrosion off and replace the vent and tank that will be fine. No need to change that just clean it up.

As far as doing the work. The water will have to be drained in order to change those parts. I cannot see your supply and return pipes to see what you have for valves. You may be able to isolate the boiler from the rest of the system to minimize bleeding but without pics cannot tell.

Depending how your system is designed you do not need air vents on baseboards (emitters) upstairs so don't worry about that for now. If you have a loop system it's bled from the basement.

You have a B&G circulator which has to be oil occasionally unlike todays wet rotor pumps. You have 3 oil cups on that pump. 1 on the bearing assembly and 2 more on the motor. Just a few drops in each. Do not over oil. It's just as bad as no oil.

You can use this oil SAE 30w non detergent motor oil or you can but regular pump oil in tubes. It's the same oil.

Pics of system would be helpful.
Hope this helps a little
Old 01-21-19, 01:51 PM
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Thank you, spott! I'll take some pics of the overall system tonight and get them posted. I do have vents on most of the baseboards but they're the manual type if I'm not mistaken. I'll grab a pic of one of them as well. Regarding the relief valve, yes, the pressure rises to 30 once the boiler has been running for a few.
Old 09-06-19, 09:17 PM
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I took some pics that night as planned, but then never got around to posting them here. Adding them now! With Fall fast approaching I'd like to proceed with replacing that defective expansion tank. Would appreciate any/all advice on tackling the job, draining the system, bleeding it, etc. I'm fairly handy but have never worked on a boiler system before.

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Last edited by PJmax; 09-07-19 at 12:01 PM. Reason: resized pictures
Old 09-07-19, 12:02 PM
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I'm not a big fan of the sheetrock touching the exhaust flue pipes.
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Old 09-07-19, 02:00 PM
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Hmm, good point. It's been that way for several years, but it'd be safer for me to trim the sheetrock back from the pipe.
Old 09-09-19, 04:01 AM
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When replacing air tank install a 1/2 ball valve on it. That makes is easier to service system without having to drain a lot of water to reduce pressure.

Replace auto vent valve with all that white cud. Use auto vent with bronze body that can be opened for service. and add 1/4 ball valve to make service easier.
Old 10-04-19, 09:38 PM
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I don't have all the parts yet, but here's my current tentative plan once all the parts are here.

1) Tighten down the water supply valve (blue handle).
2) Connect a garden hose to the drain valve and run it to my utility sink.
3) Open the drain valve. Wait for the system to drain. If/when it appears that the water supply valve is shot and new water is entering the system only to immediately leave via the drain valve (how will I know if this is the case??), turn off the water supply for the whole house.
4) Once the system is drained, remove the old auto vent, expansion tank, and expansion tank-connected elbows/pipe.
5) Clean the air scoop (how?) and the top and bottom female threads of the air scoop (how?).
6) Install the new air vent, with ball valve between the air scoop and air vent.
7) Install the new expansion tank with ball valve between air scoop and expansion tank.
8) Replace water supply valve if found to be leaking in step 3 above.
9) Open water supply valve to refill system.
10) Bleed the system. How? I found one set of instructions on, but they're written for pressure reducing valves that have a bypass lever, and mine doesn't have one of those. Without any way of feeding water into the system at house pressure, how can I bleed the system?

Did I leave any steps out? What do I put on the pipe threads? Pipe dope?

If I do need to replace the water supply valve I'll have to cut the copper pipe on both sides of it to get it out. I don't have equipment for sweating copper joints, so could I use a sharkbite fitting on both cut copper ends with the new water supply valve in between?
Old 10-05-19, 07:18 AM
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The boiler water feed valve has threaded fittings. Replace it with new ball valve.

At same time put unions either side of regulator valve. And shut off valve on boiler side of union. That way regulator can be removed for service.

You want to be able to keep heating system running on cold winter day if these things need service. A little extra work now, but makes big difference at zero F.
Old 10-05-19, 09:46 AM
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quick note..

Dont waste $$ on that boiler and near boiler piping..

It would be best to remove and replace the boiler..

A competent plumber will install all new piping and controls etc etc etc.

why spend 1k in parts for that boiler when you can have all new for somewhere in the 5k range...
Old 10-05-19, 10:38 AM
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Agreed about what is best, but replacing the boiler is not remotely in our budget right now or in the near future. So just trying to fix the necessary issues to get us by until we can afford to replace the boiler. So far the parts I have in mind are under $100.
Old 10-05-19, 07:26 PM
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This is a Do It Yourself forum for those who do not want to pay, or cannot afford outrageous prices for professionals.

The parts jessman1128 need cost less than $50 at or HomeDepot. Our local hardware stores might charge $100 which is why I do not but there.

To suggest jessman1128 pay 100 times $50 or $5,000 for new boiler is self validating lawrosa's post.

Another advantage of being DIYer is when heating problems arise on cold, snowy winter night they can fix it themselves rather than waiting in cold house for some professional.

While I can afford professionals, became a DIYer when they could not solve problems. Now get quick fixes, with no wait and little or no payment. Wife likes that!
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Last edited by doughess; 10-05-19 at 07:48 PM.
Old 10-15-19, 10:06 PM
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Time for an update!

The first stage (and possibly only stage for the time being) of the work is done. New fill valve, drain valve, expansion tank, auto vent, with shutoff valves in locations: A) between PRV and boiler, B) air scoop and auto vent, C) air scoop and expansion tank. If the pics show up in the intended order, pics 1 and 2 show the new parts.

I think I previously said there were no vents on the baseboard units. I was wrong. There are vents on almost every baseboard unit. I wasn't sure of the pressure range of my PRV (couldn't find any specs on it) and didn't want to blow out my new expansion tank, so I closed the valve to the expansion tank, unscrewed the PRV screw as much as seemed safe (web search for similar models indicated that would result in lower output pressure), and opened the fill valve. I heard water entering the system, and air exiting the auto vent. After awhile I started slowly tightening the PRV screw to increase pressure. To shorten a potentially lengthy story, I eventually got the system to where I thought it was full (pressure gauge read 25 PSI and water was dripping out of the relief valve), adjusted the pressure down to 12 PSI, and turned on the system. I could tell right away that it wasn't full from the sound of water falling down the return pipe. It wasn't a smooth sound of a pipe full of water, but more of a sprinkling sound. I had stopped hearing air exiting the auto vent sometime during the filling process, so I located the baseboard vents and started opening them one at a time until water started coming out. Repeated this process 3-5 times at each vent with the system on. The pipes feel warm at all baseboard locations now, but I'm assuming I still have air in the system and so I plan on checking all the baseboard vents a few more times over the next 2-3 days.

-Am I running afoul of any typical codes by having shutoff valves in non-standard orientations? i.e. the handle isn't on the very top. I found that it's much harder to standardize the handle location when using the threaded variety as the primary concern is to get it tight enough that it won't leak.
-Boiler gauge is showing ~18 PSI @ 180F degrees when it's running. Is that about right? I know last year with the bad expansion tank it hit 30 PSI all the time. Not sure if I ever noted the gauge temperature then.
-I found instructions for calculating my system BTU here, but it requires having the proper pump curve graph. I'm still not sure what pump, specifically, I have. From looking around online it looks fairly similar to a B&G Series 100, but it has a shorter length than what is listed on the spec sheet for that model. Complicating matters further, it has a Dayton motor, not a B&G motor. I can't find any specs for Dayton motors, let alone a pump curve graph. I found a Century-brand motor that is listed as a direct replacement for my Dayton model #, and have sent a request for its pump curve, but no idea if they'll give it to me, and if it'll even be valid for my Dayton motor. Thoughts? (Various pics included of the pump and motor label.)
-Oiling locations - the B&G label mentions oiling the pump bearings and motor bearings. I found the oil location for the pump bearings (shown in one of the pics - the square plate with a dimple in each corner). I'm not finding anything at all for the motor bearings. It seems the oil locations are supposed to be accessible without removing the motor, but that's for the newer B&G pumps that have B&G motors. At the moment I'm theorizing that it came with a B&G motor originally, but was later replaced with a compatible Dayton motor by a previous homeowner and the Dayton motor doesn't have bearings that require periodic oiling. I've included pics of the front and back of the motor housing top, and also the back, in case oil locations are visible and I'm just not seeing them.
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Old Yesterday, 07:33 PM
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The B&G Series is old technology that should be replaced by a modern Grundfos Alpha variable speed ECM pump.

Alpha is lower priced and uses 50% less electricity. Is interchangeable with B&G

You do not need BTU data. Alpha's automatically adjust to varying conditions. Alpha's have settings for automatic pressure and volume along with multi speed selection which is great for adapting to variable multi zone system conditions.

Another old fashion concept is keeping water at 180F all season. Modern “Out Door Resets” ODRs are aquastats that automatically adjust boiler water from 140F to 180F according to what is actually needed. Fuel savings with ODR's can reach 20%.

The Tekmar 256 is a best buy:

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