No certainty from pros, 6 apartment 60 y/o building

sixplex

So i live in a 6 unit apartment building, 3 floors, 50' x 50'
225K BTU Slant Fin boiler, cast iron baseboard radiators, Tekmar 256, 2x Taco 0015es circulators, 2xEcobees with wireless sensor in each apartment.

There is a single supply and 2 returns. Circ A heats up apartments 1 and 2, circ B heats up 3-6.

Big problem is that apartments 2 and 4 are always too hot, my guess is because the main supply labelled X runs between them and is always hot even when the circulators are off.

Will it be enough to install internal check valves in the circulators to mitigate this?

Ironman

Flow checks, or check valves, should always be installed anytime there are parallel loops with pumps.

Ironman

The way that's piped, I'd install one properly sized circulator in the SUPPLY line above the boiler and put zone valves where the circulators are now. That way, the circulator would be "pumping away" from the Point Of No Pressure Change like it should be which would also minimize any air problems in the highest part of the loop.

You also need an air separator in the supply line because you now have a bladder expansion tank and there’s no way to automatically purge air from the system. That should have been done when the bladder tank was installed.

Zman

You should have checks on each loop, not only to prevent thermal migration, but also to prevent reverse ghost flow when only one circ is running.
I would suggest feeling the pipes under different operating conditions to see what is really going on. One issue with series baseboard systems is that the first radiators get hotter water thus overheating the spaces. This can be mitigated somewhat by closing the registers on the units first in line. Increasing water flow to zones will also help.
In a quality design and install, the designer will increase the radiator size downstream to allow for the colder water so that all rooms will heat evenly. This rarely happens in the real world.

jumper

Ironman said:

The way that's piped, I'd install one properly sized circulator in the SUPPLY line above the boiler and put zone valves where the circulators are now. That way, the circulator would be "pumping away" from the Point Of No Pressure Change like it should be which would also minimize any air problems in the highest part of the loop.

You also need an air separator in the supply line because you now have a bladder expansion tank and there’s no way to automatically purge air from the system. That should have been done when the bladder tank was installed.

Wonder what happened to original expansion tank?
First thing that I'd try is turning off Circ A. My guess is that when new boiler was installed an additional circulator was added to make certain that basement was heated.

sixplex

Both 'zones' are original circa 1960 based on 2 thermostat wires in the basement and the top floor. Old 'expansion tank' is in the ceiling.

Installed integrated flow checks on each circulator.
Will install an air separator, i bleed air from the top rads all the time, suggestions on best model?


Single circulator on the supply sounds intriguing, but probably best considered when i upgrade the boiler.

Also there is an identical neighboring building which is identically piped, they also have 2 circulators

SuperTech

For an air separator you should definitely get any brand of microbubble resorber. Spirovent and Honeywell supervent are common brands.

Caleffi makes an excellent product that combines the microbubble resorber with a magnetic dirt separator, thats very important to have to protect modern ECM circulators.

Ironman

Any type of Micro Bubble Resorber: Spirovent, Caleffi, etc.

mattmia2

The cold could be from trapped air preventing circulation or full contact with the pipe.

Are you sure the part on the lower left is really how those pipes connect up? is there a valve or check valve anywhere? If pump b is off, pump a is mostly going to circulate around the loop of both floors.

sixplex

That's guys ! I will report back when the heating season starts on the difference the integrated check valves and the air separator made.

sixplex

So... the Integrated Check Valves did the trick! The 2 apartments closest to the boiler don't overheat.

The 10 feet of the supply immediately from the boiler still get plenty hot from the boiler short cycling to maintain it's temperature. Is there a good reason to install a check valve there?

Larry Weingarten

Hi, Might it be easier to just install really good insulation?

Yours, Larry

sixplex

There is obviously an air intake opening next to the boiler, which cools down the boiler really quick, insulation or not. I already added some fiberglass insulation, didn't help.

Air is still an issue, did not put a micro bubble separator this season. Thinking next season i'll do it properly and start pumping away... as per ironman's suggestion the only issue is if i replace the 2 pumps with 1 pump. I won't be able to heat 2 "zones" simultaneously because if i put in a pump twice as powerful, it'll be too noisy when only the lower zone (lower head) is calling for heat. And if i try heating 2 zones with only one of the existing two pumps chances are the flow won't be sufficient.

Ironman

One properly sized ECM Delta P circulator would carry the entire load and vary its speed depending upon the number of zones calling.