What is this on my drain line?

[colinnwn]

Hi,

I'm trying to figure out what this is, connected to the drain line in the service closet of my 1960 house. It is right below a toilet and tub. I'm guessing it is an air admittance valve. But I don't see how it keeps out sewer gasses, and I don't see why this was necessary when there is a roof vent as well.

If it is an air admittance valve, I'd like to replace it with one of the new low profile engineered air admittance valves, because this blocks access to remove my water heater on the left side of the pic. But all the ones I have found say they must be installed above the highest backup point in the drain line. This is obviously below that.

Thanks.

 

[Caduceus]

I don't believe it to be an air admittance valve, but I don't know what it truly is.
It doesn't look like anything that would be related to the function of the plumbing system, but the design and the steel fittings lead me to believe that there may have been boiler water or steam heat in the house before and this may have been for drainage or pressure blow out.
If I see the steamfitter today, I'll show him the pic.

 

[Caduceus]

Steamfitter and AC mechanic don't recognize it either.
I'll take a look in the Audel's book tonight.

 

[colinnwn]

boiler water or steam heat in the house before

Thanks for any help identifying it. But I don't think this will be it, as this house is in Texas, and I have never heard of any residential boilers or steam heat here. This is a 2 owner house with virtually no changes since it was built, and there is no other evidence in the house of it having steam heat, or being that unique.

-Edit- sorry just saw your 2nd reply.

Just thought to mention in case it helps with clues, that the washing machine used to be in this room. And the house didn't have a TPR drain line built into it. Right now it goes into a floor drain. Perhaps the TPR used to be plumbed into the sewer drain line, and this was for the steam relief if it did blow?

 

[IFIXH20]

Possibly the old standpipe for the washer and someone gave it a half turn because it's not in use anymore. Looks like it needs to be capped to prevent sewer gas spillage.

 

[colinnwn]

Possibly the old standpipe for the washer

That hadn't crossed my mind but it sorta makes sense. The only oddness is it would be a little high and small diameter for current standpipes. And there is an approximate 1.5 in to 3/4 in reducer on the end I'm not sure why they'd put on there instead of capping.

 

[Caduceus]

The standpipe is a good thought and it could have been for something else other than a washer, too. Can't understand why black steel and galvanized fittings would be used, but I think IFIX has the right idea.
If it's not important to the plumbing system, I would remove it and put a plug into the cast wye for clean out access then recycle the copper.

 

[IFIXH20]

I thought just maybe a standpipe. Bare with me here. Old school DIYer removed the clean-out cap and used iron pipe/copper fitting because he did not want to cut into the cast iron (not as many nowadays fitting back in the 60's). The other thing came to mind is older DIYers love to put 3/4'' galvanize nipples in the washer drain hose to restrict the water flow when the washer drains because the drain would not accept the water quick enough ( drain needed a good cable cleaning). We know it's not the proper size or height. It just looks like a old school DIY to me and I could not come up with anything else.

 

[user 7082]

The sweat copper portion attached to galvanized steel pipe, as someone else mentioned, looks like it was swung out of the way. If you imagine swinging it back, then the copper reducer fitting seems a perfect fit for the drain line attached to the pressure relief valve of the water heater. You can, in the photo, see a copper sweat coupling that appears to be the correct height to attach to the reducer, if swung upright again. I wonder whether this was attached to this water heater or the same on an older water heater.

 

[colinnwn]

You can, in the photo, see a copper sweat coupling that appears to be the correct height to attach to the reducer, if swung upright again. I wonder whether this was attached to this water heater or the same on an older water heater.

That's actually the cold water line to the heater. The PVC pipe in the bottom of the pic goes to the TPR valve, which the piping was definitely changed as an afterthought when installing this heater. This is another excellent possibility of how the past water heater was hooked up.