Control two circulators with L4081B

Heap

I have a Weil-McLain gas boiler,hot water base board heat. A New Yorker oil burner was removed. The installer tried to hook up two circulators to a L4081B. The themostats are 115v old T451 thermostats. As far as I know, the oil furnace was wired so that two circulators were controlled by the low limit side of the aquastat. There were no relays and no 24v supply. The installer is now very confused,and now wants to replace thermostats and wiring to circulators from the low setting side. I`m not an expert in gas boilers,but I have a background in some controls,electronics,and electrical wiring. It seems to me that his first idea about wiring two circulators through the low limit setting is valid,but maybe not widely practiced. All diagrams for the gas boiler only show connections for one circulator,and 24v thermostats. The wiring that was common,I`ve been told,on old 115v systems thermostat systems on Long Island,were simply both circularors in a two zone system, each in series with its controlling 115 thermostat,and additionally controlled by wiring through the low limit side of the aquastat. I traced the old wiring from the thermostats. If this was once hooked up this way,and worked for 40+ years, why not now? The logic for gas or oil boiler should be the same,I would think.

                             Gene H   Long island

 

Tim McElwain

What is the Model number

of the Weil-McLain boiler? What are the controls on boiler, does it have a control center or an aquastat relay?



Typically with two circulators you are looking at a 2 zone system. One circulator connected to the control center or off C1/C2 on the aquastat relay. The relay should be controlled by a 24 volt thermostat.



The second circulator can be controlled by an switching relay such as an RA 845 Honeywell relay just make sure the burner circuit terminals 4 & 5 are wired through the high limit on the aquastat control. This relay also uses a 24 volt thermostat.



You will have much better efficiency using the 24 volt thermostats as they typically can have an anticipator for better cycling control. You can also get programmable thermostats with setback control for operating based on your living habits.

Paul48

This is what he's decribing Tim

http://customer.honeywell.com/techlit/pdf/PackedLit/60-2105.pdf

Paul48

How

it the installer doesn't know what you have, or what he installed?

Empire_2

HEAP, a few Q?...

Like Tim asked, what other if any controls are you looking at?  If you are using the (L4081) controller the "T"&"T" was probably jumped.  Is that correct?  The Lo Limit side of the control will cut off both pumps in your description (Not just 1) and not be zoned for 2 separate zones.  Even if that were, how is it wired, It must be uncomfortable.  Also, if TT is jumped out, it will always be calling when power applied and each individual stat will bring on the pump that it is designated for.



Mike T.



More Info would help.   

Empire_2

HEAP, a few Q?...

Like Tim asked, what other if any controls are you looking at?  If you are using the (L4081) controller the "T"&"T" was probably jumped.  Is that correct?  The Lo Limit side of the control will cut off both pumps in your description (Not just 1) and not be zoned for 2 separate zones.  Even if that were, how is it wired, It must be uncomfortable.  Also, if TT is jumped out, it will always be calling when power applied and each individual stat will bring on the pump that it is designated for.



Mike T.



More Info would help.   

Empire_2

Tim, Not sure?

Tim I am not sure if he replaced the boiler or just the power burner or what?  I guess until a reply is posted it's only a guess as to what is actually there.



Mike T.

Paul48

It's

one of the most useless aquastats I've seen. Simply, two thermostatic contacts. No transformer, and the "B" is just hi-limit and circulator control.

Mac_R

If it were me.

I would just spend the money and update the entire control package and circulators.  Go with a Beckett AquaSmart for the main boiler control and use a couple of Taco Delta T 008 circulator pumps.  The nice thing about using the Delta T pumps is they have a set of dry contacts that can be used with a thermostat to turn them on or off.  Then wire one to tt on the AquaSmart and the other to ZC.  If you are interested I could work up a wiring diagram.