Aquastat question

[ewdudley]

Seems like the wood boiler could spend a lot of time ready and willing to supply heat, but the 401 will keep it valved off when it's most needed.

That's the way I understand it. That Tekmar control is for a SINGLE boiler, either two stage or modulating, assuming I read the manual correctly.

It looks like RMan and I agree that the stage 2 output of the 401 is not going to work if the intent is to switch over to oil when the wood boiler goes offline. Neither can the stage 2 output serve to supplement wood boiler output if and when wood boiler falls behind temporarily, at least not in the case where the three-way valve is configured the way it is.

I think what you may want is to have a switch, in conjunction with a relay or two, that directs the stage one call for heat to the wood boiler or alternatively to the oil boiler as appropriate. It could be a manual switch to get you going, with the option of adding an aquastat to the wood boiler side that would automate the switch-over.

Once you're sure how you want the system to work we can worry about how to connect to the three-way valve and the aquastat.

 

[McKraut]

It looks like RMan and I agree that the stage 2 output of the 401 is not going to work if the intent is to switch over to oil when the wood boiler goes offline. Neither can the stage 2 output serve to supplement wood boiler output if and when wood boiler falls behind temporarily, at least not in the case where the three-way valve is configured the way it is.

I think what you may want is to have a switch, in conjunction with a relay or two, that directs the stage one call for heat to the wood boiler or alternatively to the oil boiler as appropriate. It could be a manual switch to get you going, with the option of adding an aquastat to the wood boiler side that would automate the switch-over.

Once you're sure how you want the system to work we can worry about how to connect to the three-way valve and the aquastat.

Right now I have a switch that supplies power to the oil burner. It has been off since I've opened this thread. At this point I will just leave it this way. I appreciate your help. This has been extremely frustrating. I thought I hired qualified people to design this for me, but in the end I got the shaft. No wonder they went out of business. I don't have enough experience with relays, switches, or aquastats to do anything else with the set up.

Bob

 

[R Mannino]

I think you can get it to work with your existing controls, maybe not ideally. The question is what closes T-T on the Aquasmart? If we add a RIB relay as an end switch to the three way valve the system should work. Has the Tekmar been able to move the three way valve?

 

[McKraut]

I think you can get it to work with your existing controls, maybe not ideally. The question is what closes T-T on the Aquasmart? If we add a RIB relay as an end switch to the three way valve the system should work. Has the Tekmar been able to move the three way valve?

When there is a call for heat, on the Tekmar display, the call for boiler one (wood) is displayed, then within a few minutes the display shows boiler two -- or stage two (oil). At that time the three way valve closes and the boiler fires (if there is a low limit set).

Bob

 

[R Mannino]

The real question here is why does the Tekmar go to stage two so quickly. If I didn't know any better I'd say it should stay at stage one unless the control sees the boiler supply temperature dropping.

The three way valve just needs an end switch to fire the boiler cold, without a low limit set.

The real problem here is why is it going to stage two so quickly?

EW, your up! How's the weather up there my daughter is driving home from Oswego on Thursday?

 

[McKraut]

The real question here is why does the Tekmar go to stage two so quickly. If I didn't know any better I'd say it should stay at stage one unless the control sees the boiler supply temperature dropping.

The three way valve just needs an end switch to fire the boiler cold, without a low limit set.

The real problem here is why is it going to stage two so quickly?

EW, your up! How's the weather up there my daughter is driving home from Oswego on Thursday?

I have contacted Tekmar directly, 2 Tekmar representatives, to ask for so help and advice and nobody will even give me the courtesy of a response. I'm not very impressed with them.

Bob

 

[R Mannino]

The Tekmar controls are pretty powerful with regard to the number of things they're able to do. System wise it seems like your "right there" just a matter of tweaking what you have. I'm not really a wood fired expert other than the Harman Oakwood I have, but I've put in a couple of heating systems here and there.

 

[McKraut]

The Tekmar controls are pretty powerful with regard to the number of things they're able to do. System wise it seems like your "right there" just a matter of tweaking what you have. I'm not really a wood fired expert other than the Harman Oakwood I have, but I've put in a couple of heating systems here and there.

You know a helluva lot more than I. I am totally lost.

Bob

 

[ewdudley]

The real question here is why does the Tekmar go to stage two so quickly. If I didn't know any better I'd say it should stay at stage one unless the control sees the boiler supply temperature dropping.

But the "Boiler Supply Sensor" is on the "Supply Header" with as many as four circulators trying to pull as much heat as they can, so maybe it's not surprising that the 401 would go into stage 2 high fire.

But I don't think that matters, I don't see how the oil boiler can be controlled by the 401 stage-two-high-fire relay in the first place. With the three-way valve set up the way it is either one boiler supplies heat or the other, and I say that when one boiler is running the other needs to be offline. But the 401 has the wood boiler activated by the stage-one-low-fire relay, which I assume stays active the whole time. The system needs to decide which boiler is online and the 401 is not the right controller for that.

The three way valve just needs an end switch to fire the boiler cold, without a low limit set.

According to the actuator sheet there needs to be three wires and a switch to control the valve:


But there's only two wires coming from the 401 side, so I believe the fact that the valve does open and close when the aquastat is in low-limit mode means that 24 VAC coming from the aquastat side is somehow involved, how I don't know and don't care. As you (RMan) have pointed out upthread this can't be good.

So need to set it up so the 401 stage-one-call-for-heat signal can switched to activate wood boiler T-T in one mode and the oil boiler T-T in the other.

Need a separate switch to activate the three-way valve continuously while the system is in oil boiler mode. The three-way valve should not be activated according to call-for-heat, it should be activated according to which boiler is on line. I don't think the valve actuator needs an end-switch function, when the oil boiler is on line the valve function and the call for heat function are independent, which is to say the loads need to be able to circulate through oil boiler whether it is firing or not.

EW, your up! How's the weather up there my daughter is driving home from Oswego on Thursday?

They're getting hammered by the looks of it. Only fifteen miles away from where I'm at but it's a whole different world with the wind straight out of the west like it is now. The good news is once she gets a few miles south and east it should be just fine.

 

[McKraut]

the loads need to be able to circulate through oil boiler whether it is firing or not.

I always thought that it wasn't a good idea to run heated water through a cold boiler -- due to heat loss up the chimney

Can the problem be corrected by switching to a different controller or by changing the piping?

 

[ewdudley]

the loads need to be able to circulate through oil boiler whether it is firing or not.

I always thought that it wasn't a good idea to run heated water through a cold boiler -- due to heat loss up the chimney

I mean when the oil boiler is the active boiler it doesn't make sense to me to close the valve to the boiler when there is not a call for heat. Normally when an oil boiler is online the loads circulate through the boiler and the burner cycles to supply heat and to keep the boiler jacket above condensing temperature.

When the oil boiler is offline then the three-way valve would be closed and no water would circulate through it.

 

[R Mannino]

I always thought that it wasn't a good idea to run heated water through a cold boiler -- due to heat loss up the chimney

Can the problem be corrected by switching to a different controller or by changing the piping?

You could eliminate the 3 way valve and pipe the oil boiler primary-secondary and use the Aquasmart to power the circulator on that loop.

The bigger issue is there is no call to T-T on the Aquasmart. What kind of backup with the oil are we looking for? You could just wire a cheap thermostat to T-T on the Aquasmart to generate the call for heat.

 

[R Mannino]

Do you have any photos? I ran into a Northeast Radiant Technology job today.

 

[McKraut]

You could eliminate the 3 way valve and pipe the oil boiler primary-secondary and use the Aquasmart to power the circulator on that loop.

The bigger issue is there is no call to T-T on the Aquasmart. What kind of backup with the oil are we looking for? You could just wire a cheap thermostat to T-T on the Aquasmart to generate the call for heat.

Here are pictures of the piping. I have not hooked up the DHW circuit yet. Do you see any problems with the piping? There is one problem I will run into in the future with storage.

Bob

 

[McKraut]

Yes, I know the actuator isn't on the 3 way valve. I pulled it off because I was tired of dealing with it.

Bob

 

[R Mannino]

Where is the boiler supply sensor from the Tekmar located in the photos? It looks like it's on the supply from the Buderus.

I think I can say with confidence it's not where it should be and it's not where the diagram says it should be.

I would put it just to the right of the three way valve, just before the first tee for the first circulator. Now we just have to figure out how to close T-T on the Aquasmart.

 

[R Mannino]

Get one of these (broken link removed to http://www.functionaldevices.com/building-automation/display.php?model=RIBU1C)

Take the wht/blu wire to one of the stage 2 terminals on the Tekmar and the wht/yellow to the other stage 2 terminal.
Then take the yellow and orange wires one each to T-T on the Aquasmart. Cap the wires you don't use.

(broken link removed to http://www.functionaldevices.com/images/diagrams/RIBU1C.jpg)

 

[McKraut]

Get one of these (broken link removed to http://www.functionaldevices.com/building-automation/display.php?model=RIBU1C)

Take the wht/blu wire to one of the stage 2 terminals on the Tekmar and the wht/yellow to the other stage 2 terminal.
Then take the yellow and orange wires one each to T-T on the Aquasmart. Cap the wires you don't use.

(broken link removed to http://www.functionaldevices.com/images/diagrams/RIBU1C.jpg)

The relay just showed

Where is the boiler supply sensor from the Tekmar located in the photos? It looks like it's on the supply from the Buderus.

I think I can say with confidence it's not where it should be and it's not where the diagram says it should be.

I would put it just to the right of the three way valve, just before the first tee for the first circulator. Now we just have to figure out how to close T-T on the Aquasmart.

Holy sheet! I feel stupid. I can't believe I did that. I don't have even have anybody to blame for that one. I got the relay delivered from Amazon yesterday. I am not off work until Thursday so I will be taking care of it then. Thanks for all your help.

Bob

 

[R Mannino]

Let us know what happens.

 

[McKraut]

Let us know what happens.

It didn't work. There was no difference, that I saw, before the relay was attached. I did notice that the red light did not come on after I wired it up. Would this be a problem? I verified that I wire it the way you had posted above. Any other recommendations?

Bob

 

[R Mannino]

Is the Tekmar still moving the 3 way valve?

 

[McKraut]

Is the Tekmar still moving the 3 way valve?

Yes, it did.

 

[R Mannino]

Try wiring the RIB at the three way valve on the two terminals that have 24 volts when the three way is positioned for flow at the oil boiler.

 

[McKraut]

Try wiring the RIB at the three way valve on the two terminals that have 24 volts when the three way is positioned for flow at the oil boiler.

I wired wh/blu and wh/yel to the actuator and yellow and orange to the Aquasmart. When the TEKMAR calls for Stage 2, there is no movement on the actuator.

Bob

 

[R Mannino]

Are we sure we didn't move any wires from their original position? RIB relay gets wired in parallel with the actuator.