Can the boiler be the air scoop?

bruce_21

I wonder if the piping in this picture works. Looks like the boiler is the air scoop. Do I need to repipe this or will it work as is?

icesailor

The Scoop:

Judging (by me) from all the air vents that I cranked the caps down tight to stop leaking, and that went for years without a problem with any form of air, I'd say from my experience, it will work just fine. Once you get all the initial air and you keep the system pressure at least 15#. That one above the supply tee with the vent on it, becomes the air eliminator. Is that Tee tapped with a 1/8" IPS tapping? That fitting alone would have cost more than a Amtrol type 1 1/4" 3000 scoop and tank kit. It looks like it has been working for a long time. Don't argue with success.

But, where's the expansion pressure device? It should have at least a #60 or equivalent .for cold start water expansion.

IMO

bruce_21

another picture, closer up

Here is the expansion tank with another little vent.

hot_rod

how has the system performed

looks like it has been in service for some time. Does the system operate quietly?



That is really a "high point" float vent. It really doesn't do a great job of getting micro bubbles or entrained air out of the fluid stream.



If the boiler has a large space in that section, that can be the "low velocity zone" which allows air to separate and rise up to the vent.



The fact that there are multiple float vents installed may indicate an air removal problem. Those large pipes can be a challange to get air removed, you need at least 2 fps velocity to push air along with the fluid stream.



There are vertical microbubble type air separators on the market if you feel the system needs better air removal, it would be easy to install a vertical above the circ.

icesailor

Support:

If that Extrol tank fails and fills with water, it will break that copper tube from the adapter and very bad things could happen when the water runs out of the system and all over the floor. If you've ever tried to unscrew a water logged one, it doesn't weigh anything until it comes off the last thread. If you have your foot under it, you will quickly realize why you should never put your foot under a waterlogged Extrol while removing it. Tie a 5 gallon bucket to the pipe and let it fall into the bucket.

Because that is a cold start boiler, I think it needs more expansion. Like another #30 or a added #60. And supported somehow to take the weight off of the copper tube.

icesailor

Old Systems:

I'll bet it has given years of trouble free service. The Taco 007 was replaced with the Grundfoss 3 speed. The old exhaust has been reduced from the original boiler that probably has a ceiling mounted compression tank, and there's a old RC on the floor.. The old compression tank might have leaked and been replaced with the quickie connect on the expansion/compression location.

Its not always wise to turn a simple job into a project. I'd bet that the old tank is still in the ceiling over the boiler. If not, you could probably find where it is.

RobG

Relief Valve

Is there a relief valve on that thing? If it's on that pipe going back to the left it should NOT have a valve on it. Was it taken off to install that float vent?



Rob

icesailor

Relief Valve:

Rob,

I think if you look closely below the 3/4" tee to the expansion tank, the relief valve is installed. Improperly. When the expansion tank failed, the added a tee to put the Extrol in and moved the vent up. The air vent on the supply might be where the old compression tank was, Either way, it looks like they did a quickie Extrol install. The price was right .

You never know what you will see on an old boiler replacement.

hot_rod

keep an eye

on that boiler, I don't see any return temperature protection. It looks like a lot of mass and water content if the building is piped with big steel pipe. That boiler may operate in condensing mode for some time at startup.

bruce_21

another thought

Thanks for all the helpful comments!



I'll check the expansion tank piping (I think its steel) and find the relief valve (I think its coming off the back of this Peerless three section boiler).



I have another idea I'd like your opinions on: since this is a high mass situation with cast iron radiators and big steel pipe (was maybe a gravity system originally), would it work to run the circulator continuously and change the controls to an outdoor sensor that would then vary the boiler temperature? Are there condensation or other issues if the output temp stays at something between 120 and 160? The house is small and has thin walls which likely had little insulation and leaky windows originally, now new windows and spray foam insulation is going to cut the load way down so I'm thinking comfort will go up if there are no big swings in temp from the system overshooting the thermostat setpoint because of all the water mass.