Flushing a boiler?

[DeerSlayer 241]

Yup... If the gauge is there and if it works.

If it doesn't have one that works, just screw one on a boiler drain. I have a pressure Guage in the truck with a female hose adapter on it.

[siderman 1,137]

Siderman,

 

I'm in the business also. 95% of the noise issues I come across- are air related. I would give the system a good purge first, as long as your near boiler piping is correct. Next, I would do as Deerslayer suggested, and add a micro-bubble removal device (Spiro-vent, Honeywell PV, B&G). Remove the can vent.

 

Check your piping- Is the pump pumping away from the expansion tank/fill valve? You can find a ton of useful info on heatinghelp.com regarding near boiler piping. 

 

Your heating system is a closed system, it shouldn't be getting fresh water so it shouldn't see scale build up like a water heater.

 

If you could, take a video of the noise and post it. Deerslayer or myself could probably tell right away from the noise if it is scale or air.

 

Shane

Thanks for weighing in. Why are all the heating guys around here so far away?lol  Any locals to Bergen/Passaic? I know its a closed system and wondered how a finite amount of water could cause scaling. Pretty sure of no leaks, no sub grade piping but plenty of in wall, under floor and crawlspace but you'd think a stain or wet spot would show. Good idea on closing the feed and check the guage, guess that would take a while to register.  The new vent is just over the boiler on the feed pipe so I'll give that time to work as I think the old one wasnt,  but this whole issue is relevent to heating and that hasnt been run in months. I also just thought of something else, about 3 yrs ago the indirect hot water tank and its exp can was replaced and maybe some air got introduced then? It does have its own dedicated zone and operates the boiler yr round but the noise is much louder running heat.. I know I'm fixated on the scale but maybe hopefully it is just air.....I can build a house but for some reason not comfortable and no experience working with water and boilers but a system purge looks like it is in order but will be a pain with 4 zones + hot water, buckets and a pump because no drains nearby which. I want someone else to do this or show me how lol.  ,pay in cash,ammo? 

[DeerSlayer 241]

Thanks for weighing in. Why are all the heating guys around here so far away?lol Any locals to Bergen/Passaic? I know its a closed system and wondered how a finite amount of water could cause scaling. Pretty sure of no leaks, no sub grade piping but plenty of in wall, under floor and crawlspace but you'd think a stain or wet spot would show. Good idea on closing the feed and check the guage, guess that would take a while to register. The new vent is just over the boiler on the feed pipe so I'll give that time to work as I think the old one wasnt, but this whole issue is relevent to heating and that hasnt been run in months. I also just thought of something else, about 3 yrs ago the indirect hot water tank and its exp can was replaced and maybe some air got introduced then? It does have its own dedicated zone and operates the boiler yr round but the noise is much louder running heat.. I know I'm fixated on the scale but maybe hopefully it is just air.....I can build a house but for some reason not comfortable and no experience working with water and boilers but a system purge looks like it is in order but will be a pain with 4 zones + hot water, buckets and a pump because no drains nearby which. I want someone else to do this or show me how lol. ,pay in cash,ammo?

Every time water enters the boiler for any reason, you're always introducing air in the form of microbubbles. Just like when you fill a glass from the sink, you can see the tiny air bubbles in the glass. Eventually they all collect in one place in the system. Usually at the highest point in the system. Sometimes you get an air pocket at the circulator pump, and it can start to cavitate. That's pretty noisy. This is why an air scrubber is a great idea. Boilers usually treat the water that's in them, and scaling is rare. Inside an indirect, or built in tankless coil is usually where minerals collect. But that's usually on the domestic water side, not the boiler water.

 

I can explain to you how to purge the system, but if you screw up you will be blowing off your relief valve, and they usually don't stop leaking afterwards. I start off by killing the power, then closing the valve on the return, then connecting a hose to it on the return above the valve you closed below, from there I opene the by pass on the pressure reducing valve giving it full house pressure then I manually open the zone valve to the first zone locking it open if it's a Honeywell or Erie valve, I kink the hose in my hand and watch the pressure side of the gauge (the relief valve blows off at 30psi) you want to Un kink the hose around 27-28 psi before you blow off the valve. Then let it run out till the pressure drops to about 15lbs, don't let it go below 10 lbs or you will be introducing a ton of air into the system defeating the entire purpose of purging in the first place. Then you just do each additional zone one at a time, closing the zone valve on the last one you did, as you open the next one. Leave the boiler between 12-15 lbs when your finished, and you close the by pass.

 

Some boilers use multiple circulator pumps instead of zone valves, there should be a valve on each zone to isolate them instead of zone valves. Also some guys pipe a boiler drain on each return, so if that's the case you have to move the hose to each drain which is a royal pain in the ass. Make sure you check all the packing nuts are tight on all your boiler drains afterwards, and that you put all your zone valves back to automatic. Then restore power and you should be air free for the most part. But without an air scrubber, you will be doing the same thing in the future.

[siderman 1,137]

Thanks for the write up. I just watched about 5 youtubes and it looks like a pc of cake. Didnt see any hose kinking tho, must be your patented trick. I'll get to the purge just before heating season kicks in so I can tell if air was the culprit when the heat gets used a lot. If so, I'll consider an air scrubber too.

[DeerSlayer 241]

Thanks for the write up. I just watched about 5 youtubes and it looks like a pc of cake. Didnt see any hose kinking tho, must be your patented trick. I'll get to the purge just before heating season kicks in so I can tell if air was the culprit when the heat gets used a lot. If so, I'll consider an air scrubber too.

I kink the hose to build the pressure up. That helps to flush out any trapped air. You have to do it a bunch of times to each zone. Build pressure, then release until you don't hear anymore air coming out. If you have a 1/4turn boiler drain you can open and close it quickly, then you don't have to kink the hose to build pressure.

[siderman 1,137]

Quick up date , and thanx to those who helped with info. I replaced the one vent on the fresh water intake stack and purged all 5 zones. Dont recall seeing any signifigant air escaping unless it was in the initial push out the hose but the boiler is much quieter now and no clanking & banging worth concern, that was driving me nuts lol. I'd put in some more air scoops but there's basically no accessable horizontal runs with any clearance to do so so it is what it is.