Old furnace zones

[Jimmy k]

Have an old furnace from 1957…in basement of two story home..it Always just a had a single zone with thermostat on first floor..at some point a second zone and thermostat was added on second floor..I can see that all the risers from the main loop were cut off and capped..then pex was used to return the risers and and tie n to supply on top of boiler..and They ran a new return pipe along side of the original one. Both thermostats seem work as they both turn on the furnace when dialed up…the issue is that when I turn the heat on at second floor the heat on the first floor comes on as well until reaching temperature at second floor thermostat setting..If I turn the first floor thermostat to off…the first floor loop will run as hot as if it’s set to 75 when I turn on the second floor thermostat…..I have Basic understanding of newer boilers..but I have no idea if there is something wrong..or is this just how it’s set up to run…very confusing..I added pics…when I look at the set up..I don’t know how water would stop running the first floor loop and it looks like there is no zone valves at top of furnace..but I have no idea….would appreciate any help!!!

 

[Fitter30]

Turn on second floor, first floor stat all the way down. Small pump comes on with boiler. Larger pump not running close valve at larger pump. Second floor radiators should get hot as first floor cools down. After this test close valve turn stat down first floor open valve the opposite should happen. If true need check valves at both pumps. Your 1957 boiler is costing u $$$ every month.

 

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[Jimmy k]

When I turn thermostat up on second floor…boiler turns on …but both circulator pumps run… my thought was that if the heat is off on first floor then only the circulator pump that should be running is the smaller one that is on the second floor loop..so I’m thinking it’s something electrical like a relay or the aquastat

 

[Fitter30]

When I turn thermostat up on second floor…boiler turns on …but both circulator pumps run… my thought was that if the heat is off on first floor then only the circulator pump that should be running is the smaller one that is on the second floor loop..so I’m thinking it’s something electrical like a relay or the aquastat

Looks like both pumps tie in going into bottom of boiler. First floor turns on bigger pump second floor turns on both pumps? Cast boiler like yours doesn't matter if the smaller pump or larger runs by itself. Without a check valve i each circuit water could run backwards through the other circuit

 

[Jimmy k]

Yes both tie in to bottom of boiler I will check today when I get over there…get a better pic…and look for check valves..ill respond later today..thanks..I’m assuming if a check valve is needed it would be on first floor return pipe?

 

[Fitter30]

Yes both tie in to bottom of boiler I will check today when I get over there…get a better pic…and look for check valves..ill respond later today..thanks..I’m assuming if a check valve is needed it would be on first floor return pipe?

When there was just one pump didn't need any checks. House was just one big zone and room temp was adjusted by the valve at each radiator.

 

[Jimmy k]

So I looked at it again…it’s baseboard heat on both floors…has no check valves that I can see… the switching station is a one zone that seems to be wired to second floor heat..green light stays on and then red light comes on when second floor stat is activated…I have stat Completely off on first floor…when I turn stat up past room temp on second floor ..boiler turns on..both circulator pumps are activated and heat comes on to both floors ..if fact the first floor heat is hotter than the second floor..yet the first floor stat is off….so if I want to warm up the second floor ..by the time it warms up to desired temp..the first floor is super hot..so I now have second floor stat at 65 and keep the first floor stat off…this seems to be the only way to balance the heat somewhat??

 

[Fitter30]

So I looked at it again…it’s baseboard heat on both floors…has no check valves that I can see… the switching station is a one zone that seems to be wired to second floor heat..green light stays on and then red light comes on when second floor stat is activated…I have stat Completely off on first floor…when I turn stat up past room temp on second floor ..boiler turns on..both circulator pumps are activated and heat comes on to both floors ..if fact the first floor heat is hotter than the second floor..yet the first floor stat is off….so if I want to warm up the second floor ..by the time it warms up to desired temp..the first floor is super hot..so I now have second floor stat at 65 and keep the first floor stat off…this seems to be the only way to

Second floor thermostat is feeding both first and second floors and through first floor turning on the boiler. Someone needs to figure out the out wiring. First floor feels hotter because there is more flow piping is larger as with the pump.