Wiring Tekmar Outdoor Reset to Honeywell Aquastat

nz

Hello,

I have a Honeywell L4081A1023 Aquastat (works fine), and I am adding a Tekmar 260 Outdoor Reset.

This is my first time doing this, so I am not sure which wires on the aquastat need to be connected.  I have downloaded the manual for the aquastat, but I'm not sure which wires need to be to be connected to fire the boiler? 

Also, I'm looking for advice on how I should adjust the aquastat to work with the outdoor reset so they are not fighting with each other. Should they be wired in series or in parallel?  Should the high and low be higher or lower that the outdoor reset? 

I have attached a photo of the wiring inside the aquastat. (Yes, I have the temp turned down now since it's not that cold outside.)

Any advice would be greatly appreciated. 

pedmec

your gonna have to give more info. 4081a is just make or break switches. you should post a pic of the wiring diagram. it's normally on the backside of the cover. the color of the jacket looks like a weil mclain so that's where it should be

STEVEusaPA

You’re in way over your head.

nz

pedmec said:

your gonna have to give more info. 4081a is just make or break switches. you should post a pic of the wiring diagram. it's normally on the backside of the cover. the color of the jacket looks like a weil mclain so that's where it should be

Thanks, you're right it's a WM LGB-6, here's the diagram.

nz

STEVEusaPA said:

You’re in way over your head.

I got the Tekmar wired up and working fine, thanks. Just need to know where to wire terminals 11 and 12. That's why I came here. 

EdTheHeaterMan

This is where I would wire 11 and 12 on this diagram.


Where is the L4081A wires go to on this diagram? these are the wrong wires for the location indicated on the diagram. This diagram does not show where the circulators are wired in. (Unless this is a steamer, then no circulators)

nz

EdTheHeaterMan said:

This is where I would wire 11 and 12 on this diagram.  Where is the L4081A wires go to on this diagram? these are the wrong wires for the location indicated on the diagram. This diagram does not show where the circulators are wired in. (Unless this is a steamer, then no circulators)

Thanks. If I'm reading this correctly, L4081A wires appear to be wired in here:


There are four circulators, they are wired separately and not connected to the boiler in any way. Each has its own transformer, relay, and thermostat.

EdTheHeaterMan

The wires you indicated are the line voltage (120 VAC) that is feeding the line side of the 24 V. transformers. The wires in this picture are for low voltage control wiring.


Did an electrician wire this up? I think not. Unless you are mistaken as to where those wires go. Can you take the cover off the LWCO and take a picture of that and also a picture from far enough back so we can see how all the wiring is run to each control?

I think @STEVEusaPA may have a point. If you are correct with the thermostat control wiring is being used for 120 VAC line voltage, i hope you have a functioning circuit breaker. If you are lucky, after those wires heat up too much, and the insulation melts off and you end up with no limit controls, one of those wires will touch a metal part of the boiler control system and short out to the properly grounded boiler and trip a breaker.

Teemok

Ed is breaking 120v and that would work but I'd rather switch low voltage if I can by braking the R wire between terminal #1 There might be a high pressure switch in that circuit. In that case R goes to 11 and 12 goes to where R did on the high gas pressure switch.


Edit: Tekmar terminal 1 and 2 are the boiler demand and they wants 24vac so transformer R and C. You can put a switch in it to disable demand.

Edit #2 Tekmar terminals 1 and 2 will accept 120v ac as a demand so jumping from the 120v power inputs is possible if that's preferred over a low voltage signal from 24v R and C

EdTheHeaterMan

Teemok said:

Ed is breaking 120v and that would work but I'd rather switch low voltage if I can by braking the R wire between terminal #1 There might be a high pressure switch in that circuit. In that case R goes to 11 and 12 goes to where R did on the high gas pressure switch. You will need to place a demand on the Tekmar by putting a jumper wire between 1 and 2. This jumper could be a switch or thermostat.

I was looking for that option BUT it appears that there are two low voltage systems on that particular LGB boiler. if you look closely the line voltage feeds two transformers that operate two separate gas valves. the only common place in that entire diagram where one set of contacts can break both LGB burner controls is at the Limit>LWCO>Limit wires on the 120 V side of the wiring. And I believe the code requires at least one of the limits be in the line voltage line on that size burner.

Let me know if you see a low voltage circuit for that L4081A (which does not have a manual reset limit as called for in the boiler instruction manual) that can control both burner circuits

EdTheHeaterMan

And one final note. the Tekmar needs 24 volts supplied to terminal #1 & #2 for anything to happen. I bet you didn't see that one. You can't use the boiler transformers either, because when the Tekmar shuts them down for OD Reset, they will be off with no power to operate the Tekmar until the 'Tekmar turns them back on, which it can't because the 24 volt power is off because the Tekmer turned them off.

Teemok

I see the double burner set up for the the larger models size 13-20. I read it as models 6-20 has the high voltage limit chain and the single No1 base wiring. Maybe I have that wrong. He has a WM LGB-6 right? It is not very clear.

Teemok

The larger models just have a second pre-wired panel module labeled No2 and the 120v limit chain cuts out both modules. Easy for him to confirm one way or the other.

EdTheHeaterMan

All I know is that the diagram he posted says LGB 6-20. @Teemok Unless there is another diagram for what he has AS BUILT I can only go with what I see. Again at least one of those limits should be on the line voltage side if only one burner control. The lower limit can act as a operator on the low voltage side. I wonder if this is getting inspected? I also wonder if he is operating the boiler on a constant temperature and running the circs for each zone thermostat. That would make sense to use ODR for that situation.

that is probably what this device did for the old boiler

On a boiler that size, and a home that large, a cold start boiler design may not be practical.

Teemok

From the manual:

4. For dual base assembly - operating control energizes controls for each base assembly at the
same time. See steps 1 through 3 above.

Teemok

I see that his operator looks like it's low voltage not high as in the diagram.

Full stop until that difference is resolved.
Other questions:
Tekmar demand could power direct from R and C unswitched. Tekmar 11 and 12 would open R to ignition.
Is OD reset wise in this systems case? That wasn't the question but should be asked.

Teemok

He did confirm it's the smallest 6 model. Yes pumps per zone unlinked to the boiler. Tekmar switching the low voltage would leave the 24V transformer live so demand stays at Tekmar terminals 1 and 2 while it controls the burner via 11 and 12

Teemok

As built vs wiring diagram differences are critical. What is that L4081A switching?

Teemok

I don't see the 120v limit chain components listed in the parts lists or located on the boiler diagram. They are shown in the wiring diagram only. Ed is correct these limits must be in place.

nz

Thanks everyone for the responses so far. I will try to answer all the questions here, and post more photos. 

This is a LGB-6 single base.
Aquastat is switching low voltage.
Circulators and thermostats are separately powered.

I pulled apart the LWCO and aquastat and took photos. Wire from boiler transformer is going to aquastat, I marked it with hashes since there are three 18/4 wires.

One wire is coiled, it goes from the aquastat to the LWCO.

One wire is flat and I added hashes, it goes from the LWCO to the boiler transformer electrical box.

One wire is flat and no hashes added, it goes from the boiler transformer electrical box to the boiler control panel. 

It looks like someone installed low and high voltage in the same electrical box, I'll fix that later.  This was installed by the largest boiler company in the Metro Detroit area, so seeing that is a little disappointing. 

The coiled wire goes from the aquastat to the LWCO, the marked wire goes from the LWCO to the boiler transformer.

The red and white on the marked wire provide 24v from the transformer. The LWCO relayed is wired in series via the red wire from the transformer, which then travels via white coiled wire to the aquastat. Blue/green in Aquastat are connected via wire nut in LWCO.

Red (coiled) on Aquastat connects back to white wire(marked). The white marked wire goes back to the boiler, connects to red (unmarked) wire which connects to the boiler control panel bottom left terminal marked 1.

Teemok

No sign of a manual reset high limit? Given this has been rewired to a non factory state, it would require me to fully understanding the as-built to say more. Not something I want to do from here. Ed's questions of code safety are valid. What you want to do can be done but a pro on site is a good idea to make 100% sure that what was previously done is safe and meets Detroit code and then adding the Tekmar can be done correctly.
In CA working on this would require a C4 license, no C36 plumbers. A professional seeing this takes on the liability of the alterations once they have seen them. They are obligated to correct code infractions or shut it down. Safety design alteration is not light work and should be done by someone skilled and accountable.

EdTheHeaterMan

The "as built" wiring does not match the factory wiring diagram. It appears that the RIB transformer is larger then 40VA. Perhaps the larger VA transformer can power both gas valves. If there is only one transformer then you are probably safe since there will be only one R and one C from one transformer that can have the Limits and the LWCO connected to that R wire or terminal that is powering both gas valves. Not sure why a LGB 6 needs 2 valves. It appears that both valves connect to the same set of burners. The Professional that wired up your system should have provided a "AS BUILT" wiring diagram to paste over the factory diagram. I know why they did not... They don't want the liability of superseding the factory diagram.

Still not up to code without at least one high limit aquastat on the line voltage side of the transformers. Perhaps you could add a manual reset L4006A or a L6006C with manual reset and leave everything else as is.

If that is the case. then you will place Tekmar 11 on the transformer R wire or terminal and the Tekmar 12 on the on the wire you removed from the Transformer R wire or terminal.

Still need the other stuff I mentioned above.

Teemok

@EdTheHeaterMan I think there's a gas boiler code that requires redundant gas valves when over a certain btu input. 199 or 399 I don't remember. It's common place. Some newer Honeywell valves have twin solenoids in one valve body to meet code. Those valves are 9VA per valve max.

I see manual resets high limits on the low voltage circuits all the time here in CA. I wonder if the limit in the 120v circuit code is oil burner related?

EdTheHeaterMan

So, without a lot of extra work I found this diagram in the control supplement for the LGB 6. I added a manual limit that I strongly recommend. (Green oval). The L4081 is wired between the LWCO.

These guys went to a lot of trouble to make a 120V LWCO work on the low voltage side of the transformers. But this is my best guess wothout tracing all the wires in the pictures.

Teemok

Add Tekmar 11 and 12 in blue line path. Nice work Ed.

Teemok

I love that C is shown grounded to earth in the WM diagram.

EdTheHeaterMan

@Teemok, I'm not too sure on the code on the high limit with residential gas appliance. I believe it can be on the control voltage side. If this boiler was in a commercial location open to the public, there would be annual inspections (in NJ and many other states) and there would be a requirement for at least one limit control on the line voltage circuit. It was explained to me that if everything failed and the boiler became a run away burner, eventually the line voltage wires would get too hot and the insulation would melt and short to ground inside the metal conduit, or to the green insulated (or bare) ground wire inside the MC cable cover. That would then short out the circuit and trip the breaker.

Since this is a residential use, the boiler installing company may have been able to take some liberties with those limit controls. I still think that it is ridiculous that they took the time to wire in the 120V LWCO to the low voltage circuit because you still need to run 120V to operate that control.

nz

Follow-up:

Thanks everyone for your feedback, it was very helpful. Finally got everything completed over the weekend, minus a few conduit fittings (I ran out, more arrive this week.)

I got the Tekmar 260 working in combination with the Tekmar 306V. I ended up replacing the old transformer-relays with Tekmar 003 relays connected to the 306V to control the circulators. Thermostats are now connected to the 306V. On the 260, I set the 260 radiator type to "6" (baseboard) so BOIL MIN = 140, BOIL MAX = 170, BOIL TARGET = 150.

I adjusted the aquastat to 140 low and 180 high, and I ended up breaking the aquastat high limit B and R contacts on the Honeywell L4081A aquastat, and connecting the Tekmar 11/12 in between. This way, if the 260 is calling for heat for some reason and the sensor fails, the high limit on the aquastat can take over and break the circuit. The low limit on the aquastat isn't firing the boiler, so the temperature is dropping below the low limit.

We're having some warmer weather now (60 degree days) so only getting heat calls in the early morning when the 2 degree night setback reverses. The boiler is effectively shut down during the day, which I don't expect to be the case in Winter. Tekmar is reporting water temperature is around 90F in the afternoon and about 80F early evening.

My concern is do I need to worry about condensing if I'm cold-starting the boiler once or twice a day during the shoulder season? The boiler takes about 12 minutes to get to 140F with the circulators off from basically room temperature. I imagine this would be substantially longer if the circulators were on. Given this concern, I disconnected the 260 and let the aquastat take over and keep the water at 140F for now.

Should upgrade my aquastat to the L6081A (or something similar) with a switch for a circulator control? That way I can stop the circulators until the water reaches the minimum temp to minimize the risk of condensing.

Or, is there better way to wire the 260 so I just keep the aquastat minimum at 140F and the 260 will just raise the water temperature as it sees fit? This seems like the better answer, although it may result in less savings during the shoulder season i suppose.

EBEBRATT-Ed

@Teemok

Yes over 399,000 double gas valves and is considered commercial. That is why a lot of burner/boilers are rated at 399

nz

Ok I figured it out, the non-standard wiring of the aquastat to the LWCO was throwing me off. I pulled it apart and re-wired it to the Honeywell diagram in conjunction with the diagram on the boiler.

Then I was able to make sense of it and connect the 260 in parallel with the Low switch on the aquastat, so the aquastat will now fire the boiler below 140 even if the 260 isn't calling, yet the 260 can keep calling if it wants more heat when it's colder outside even when the aquastat is satisfied.

Tested all safety controls - high limit and LWCO both cut off the burner.

Thanks everyone for the assistance.

I still may look into the circulator control aquastat, that would be useful for the shoulder season, if this is advisable and anyone wants to comment on that, it would be appreciated.

Teemok

If the 260 is programed well the operator/aqua-stat should be in place but mostly inactive. I like to have one control that has full "Control" and the other is a safety. I like safety's on the high limit. There's still no mention of the existence of a manual reset high limit in the 120v circuit. You are using the aqua-stat as an active parallel low limit, I think. This means the 260 has nothing thermally in series that can open it's call for heat. The original design has a manual high limit backing up the operator/aqua-stat in series.
If the aqua-stat was set as a safety high limit in series with the 260, then the 260 could fail to open it's switch or the wiring could be shorted but the aqua-stat would still open at the high limit. Also you don't want them in conflict where the 260's programing settings are bouncing off of the aqua-stat's limits or the 260 is trying to shut off while the aqua-stat holds flame on.
I don't know how your system is piped but a thermostatic boiler protection valve might be a good idea. It's fitted in the return piping and helps with fast warm ups and preventing cold shock when a cold zone comes on line with an already hot boiler. Your system may or not may not be able to use one without major re-piping.