Hot Water Lopp off Steam Boiler Suggestions

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hboogz

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Hot Water Loop off Steam Boiler Suggestions

All -

I have a hot water loop coming off my Burnham independence steam/gas boiler, as shown. I'm curious about a few things:

  • How do I properly bleed this system without introducing air into this loop? I suppose I need to T-off the red valve that's right after the TACO pump, then open up the hose valve until all the water is removed? Does this have to be done with the system turned off or on ?
  • Also, are there better pumps/circulators than the one pictured? Is there a model you prefer ? I'd like to prepare myself in the event this needs to be replaced?
  • I hear humming as the system operates throughout the run -- anything I can do to limit the noise ?

IMG_3271 (Small).JPGIMG_3272 (Small).JPG

Thanks,

Harry
 
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Dana

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The right place for bleeding the system is at at the highest floor, since that's where the air in the system tends to collect.

Hanging the pump torquing on a soldered ell like that is asking for trouble, and is almost certainly contributing to the noise issue. It needs more mechanical support to get the vibe down. Mounting it vertically so that it's pumping direction is UP relative to gravity reduces impeller-eating cavitation too (which can also add to noise levels.) While you're at it, get the flexible conduit for it's power feed out of the dirt too- put a conduit clip onto the side of the boiler jacket if you have to.

Taco makes a gazillion pump models. Yours looks like one of the -007 flavors, which is a standard pretty-good pump. Whether it's the right pump for the application depends on the pumping head of the system & boiler, and the flow requirements of the system/boiler.

BTW: Is there an expansion tank on this system? If it's a pressurized system (usually the case if you're running only hot-water radataio) normally when pumping away from the boiler as it appears in the picture the expansion tank is best between the pump & boiler, but sometimes it'll be installed nearby on the return side of the boiler (not best practice, but can still be OK.) It's hard to tell from the pics what the near-boiler plumbing and system plumbing configuration really is, but there doesn't appear to be an expansion tank in any of the usual near-boiler locations. With the expansion tank at some random placement on the system you'd get much more vibe & cavitation at the pump too.
 

hboogz

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Dana -

Thank you for the helpful reply.

Where the pump is located is the highest point in that loop. Do I shut off that valve and the hose valve next to the boiler, then bleed from the hose valve to the left of the pump ?

When you mention mechanically supporting the pump, what specifically do you suggest based on the pics? Cutting some 2x's to fit and place them between the floor and the copper pipes with some oatey galvanized strapping ? I doubt I'm confident enough to change the current position of the pump, but you suggest changing the orientation of the pump, so that the ingress/egress feeds are positioned vertically and not horizontally as they are now ?

Gotcha on the flexible conduit, I want to and plan on cleaning up the room on when the weather warms up a bit.

There isn't an expansion tank installed.
 

hboogz

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rethinking my post, I should probably come up from the floor with bricks/blocks and shim once I get close, then attach strapping ?
 

Dana

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Are you saying that all of the radiators/baseboards on the loop are in the basement, below the pump?

Is the system hot-water only, or are there steam radiators on the upper floors? (I'm going to assume that it is both, and low-pressure.)

If you re- mount the pump, rotating the ell so that is pumping straight up, the weight of the pump would then be supported by the stub of iron plumbing coming out of the boiler, with very little rotational force on the soldered copper connection. If that puts the pump above the water level in the boiler, you may instead have to re-mount the pump so that it's hanging from the return side, pumping toward the boiler, keeping all of the hot water plumbing below the boiler's water level. If you can then or tee over to re-join to the hot water radiation loop you can install either a bleeder valve or at the top of the tee.

It's common to install a vent or bleeder on a reducing tee:

AirBleedValve111DJFs.jpg
Air_Bleed_Valve_0491_DJFs.jpg


I would think that on a low pressure combined steam/hot water system with all of the radiation & hot water plumbing below the water level in the boiler, the boiler itself would become the air-purging vent- no bleeders or vents (or expansion tanks) required.

If it's plumbed so that air is getting into the system regularly or it's running primarily on the hot water loop, rarely on the steam loop, the oxygen in the water would be high enough to shorten the pump life, and you'd be going through pumps pretty often. When the boiler is constantly running steam it boils off the dissolved gases, and the oxygen content of the condensed water from the steam radiators is very low compared to fresh water.
 

hboogz

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Dana -

Tons of great information. Thanks.

I don't have the option in re-arranging the pump configuration just yet, but I'll take note for future reference. But, as I understand it, the biggest key is to make sure the pump is always installed below the Boilers' water level.

The system provides radiant heat to the basement, off this hot water loop, and provides steam to the upper 2 floors. Yes, it's a low pressure combined steam/hot water system with a hot water loop feeding the basement and steam rising to feed rads on the upper 2 floors.

I haven't had any issues with air coming into the system, but wanted to know, based on my setup, the proper way to bleed the system should it be necessary.

Also, the humming the pump makes as it circulates the water can be a bit annoying, but I'm more concerned that the system/setup as shown is installed correctly.
 

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If it's plumbed so that air is getting into the system regularly or it's running primarily on the hot water loop, rarely on the steam loop, the oxygen in the water would be high enough to shorten the pump life, and you'd be going through pumps pretty often. .

This actually happens at my brothers house. Are you referring to the TACO when you mention "it's running" ? The TACO is strictly circulating boiler water for this hot water loop, it's not playing a role in the steam side of the boiler function, that I'm aware of. Could you perhaps explain the above statement further ?Since it's role is strictly to pump water into the hot water loop, how then can i reduce the oxygen and thereby increase the lifetime of the TACO ?
 

Dana

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In a low pressure system with the pump mounted sideways there is greater potential for cavitation in the water as the impeller spins, which contributes to the noise, and the way the thing is mounted with the weight of it resting sideways on a length of pipe any vibration in the pump twangs that section of pipe like a guitar string (made worse if the natural vibrational frewquency of the section of pipe is near a harmonic of the pump hum.)

The drain spigot you have a foot or so away from the pump would be a good enough location for bleeding the system, but as stated previously, the boiler itself is going to be your bubble-trapping vent system if all of the liquid-water heating plumbing is below the water level in the boiler. It'll never limit flow from vapor-lock due to a large air bubble, it simply can't.
 

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It's amazing what you can learn form the www. Thank you for taking the time to help this IT nerd better understand plumber speak.
 

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I'm sorry Dana, but outside of removing the pump and installing in an orientation consistent with your suggestion, is there anything else plausible I can do that will limit the noise ?
 

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It doesn't really look that old, but if the pump has a gazillion hours on it it's possible that the impeller is corroded enough to be part of the noise problem. Most (all?) of the Taco pumps have replaceable impeller cartridges. I hate to just get into the part-swap-as-diagnosis mode, and this is unlikely to be the problem if it only has a handful of service years on it, and a replacement cartridge can be a large fraction of the cost of a new pump. If the think is 15-25 years old, maybe that would help.
 
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