Two pipe Venturi tee/Monoflo system possibly piped backwards

SuperTech

I've been driving myself crazy over the little details about my boiler piping. I've read every post on this site regarding Venturi tee and monoflow systems, as well as the instruction manuals for cast iron baseboards in the heating history section of this site.

Some things I have learned makes me wonder if the idiots that replaced my boiler installed it backwards. These morons didn't bother to tune the burner after installation and caused a massive puff back, so it wouldn't surprise me if they made other critical mistakes.

I've read that Venturi tees are always best when installed on the return, all mine are on supply. Also I read that other two pipe Venturi systems usually come out of the boiler in a smaller pipe and return on a larger one. My supply is 1-1/4 for maybe 25 feet then in splits to a Y and reduces to 1". Also the flow towards the Y seems wrong, some I have read about in past posts return to the Y.

The system works, but as a technician i get obsessed over the details. I will attach pictures of the tees and the Y. The one baseboard cover I managed to get off revealed the balancing valve, which is on the supply coming from the Venturi tee, this doesn't seem right to me either...

SuperTech

I didn't install the system myself because it was done before I was in the trade. If i had the chance to do it it would be much different, I would have figured this out a long time ago

STEVEusaPA

There is some ugliness, but not the worse I've ever seen. Plus it works.
The tees are preferred on the return, and maybe on both for down feeding radiation.
The bulk of that work was done many moons ago.
What's up with the TigerLoop. I bet the installer only had the 36" hoses so moved it up to the top of the boiler.
You have all the ball valves in the right places.
Why do you think the boiler was installed backwards? I'm sure the system piping was in long before that boiler was installed. Is the water flowing in the direction of the arrows on the tees?
Looks like you had water dripping out of the feed valve onto the boiler door for a bit.
Also, how close is that wood shelf to the flue pipe?
Overall, if you have the skills, and the money (and the time), you could rip it all out and re-do it, but other than some near boiler piping (exp tank, circ-pumping away, boiler protection-either piping or with the aquastat), I'd ride that boiler out for a while.
How's it run (efficiency, cycle times, condensing-yes/no?)

SuperTech

The boiler itself runs great. I dropped the nozzle size down to .65 and added a low fire baffle. Installed an outdoor reset module to the digital aquastat. Maximum flue temperature gets to about 450. ODR design temperature is zero. Aquastat has a type of boiler protection, it won't pump until it reaches 135, but I'm considering a bypass when I re-do the near boiler piping and move the circulator. Never had an air problem, which is good because I can't get most of the cast iron baseboards open.

The supply flows into the inlet side of the Venturi tees, but if that pipe was the return and the Venturi tee was on the return branch of the baseboard wouldn't the tee be in that position anyway? I read so much about this but it gets confusing, since these tees can work in different configurations.

The tiger loop was a freebie that I put in for the hell of it. I like the flex lines because I don't have to disconnect the oil line to get in the combustion chamber. Nothing was leaking, just sweating condensate, insulation will take care of that. Shelf has been there since the 50s. It's not a problem.