TurboMax domestic recirc

o311sta

Call today  1 apartment (out 16 ) no hot water in shower.

Assumption Spindle stuck on symmons valve.

Get there find out  huge temp. swings at valve (dropped 30 degrees) @ one point.

tenant says others  in  buildings noticing it too but she is the only one that has called.

There is a turbomax t 65 off the the boilers with a watts n170 mixer. ( I made diagrams on ms paint and attached)

1st thought ;  mixer needs to be "rebuilt" but when i was looking  at the way it was piped    the  recirc was  not tide in where I would tie it in. I noticed  hot water backing past the check   (that check isn't closing)  on the cold,and back down into the bottom feed .I shut the recirc off i could feel the cold move back threw the check to mixer.( see attached turboma.jpeg) I could also see the temp change  on the domestic mixed line

I have never dealt with turbomaxs' or ergos. My experience with traditional indirects  has been to put the recirc back into the bottom of the tank (preferably with gravity). with out closing the system. I  have never closed a system or used a potable expan. tank

So my question is if i move the recirc to where I have it in attached turbomax2  .jpeg will I have to add a check to keep it from going back up the mixer, hence closing the system off. I know what ever expan tank they put there can't be adequate (smaller than a extrol 15). Plus shouldn't it be on the cold?

I apologize for the lack of details but since we only take care of the plumbing in these buildings I thought the management company would have the heating company who installed the system a few years ago handle this but for what ever reason they want me to.

Thanks for any advise

Kevin

Gordan

What the first diagram shows is wacky

Basically, it looks to me like they made a cold water recirculating system, and the circulator will be fighting the mixer as it tries to mix in hot water but the check in the cold line to the mixer prevents recirc water from flowing into the tank, and therefore the hot water from flowing out. Bad for the circulator, bad for the mixer, useless for the people.

It's an indirect, cold water goes in, hot water comes out - no need to pipe it differently for recirc. There are two differences from (some) regular indirects: no additional ports on the tank that you could feed recirc into directly, and the water content on the domestic side is small - just the contents of the coil, probably about 2 - 2.5 gallons but the manual will have the exact figure. Small water content = small expansion tank, though you should also figure the water content of the hot + recirc distribution piping into that equation. Where the tank is looks fine as long as there's no shutoff valve or other flow control device between it and the tank.

What you show in the second diagram is fine, but there's nothing wrong with feeding the recirc back into the mixer - in fact, it's a good thing. It will always be cooler than the mixed temp, and it will almost always be warmer than the cold water, so you wind up having to mix less of the hot water in to reach the desired temperature. There just can't be a check valve between the recirc line and the tank cold inlet. If it were me, I'd put a check valve on both cold and hot side of the mixer (some mixers already come with these) and one on the cold supply line so that the tank, the recirc line and the mixer are all downstream of it.