How can we temporarily bypass a Burnham IQ outdoor reset?

Cliffy

Have a Burnham ESC boiler with a Burnham IQ outdoor reset.



Sometimes we'd just like it to heat the place up fast and hot; keeps the old folks happy. 



How can we bypass the control and have it run at 180?  I was thinking of adding a toggle switch on the side and wiring it to the hot water heater terminals 3 and 4, but I think that would also cause the boiler to run after the thermostat is satisfied.



How can it be done?

Jason_13

Bypass the OD reset

Yes jumping terminals #&$ on the card will simulate and call for DHW and override the t-stat demand. The control also has priority built into it so the heat circulator will shut down.

Are they using deep night set back? If so reduce the degree of setback. How many zones? Maybe change the boost time on the ODR card.

Jason_13

Bypass the OD reset

Yes jumping terminals #&$ on the card will simulate and call for DHW and override the t-stat demand. The control also has priority built into it so the heat circulator will shut down.

Are they using deep night set back? If so reduce the degree of setback. How many zones? Maybe change the boost time on the ODR card.

Cliffy

Thanks Jason

There's a Taco box that controls the circulating pumps, so that's not an issue.  And the domestic hot water comes from a different source, so that's not an issue either.  The terminals are presently unused.



My concern was that if those terminals are jumped that the boiler will constantly maintain a water temp of, say, 180 or whatever the domestic hot water is set to regardless of if there's a call for heat or not from the thermostat. 



Not the worst thing to have it maintaining the higher temperature (is it?) without any load.  Is there a better way to temporarily bypass the ODR control?

Ironman

Let's Think About This

You have o.d. reset to save energy and give better comfort, but you're also using setback for ??? Then coming out of set back, you want to disable the o.d. reset because it takes too long to recover for the old folks (even though the control has boost). Now you're considering simulating a domestic call to run the temp to 180* even though doing this will cause the boiler to continue to fire after the thermostat has turned off the circ. and there's no flow through the boiler? And you think all of this is a good idea??



Please tell me they don't let you have any sharp objects.

Cliffy

huh?

I never wrote of setbacks and recovery, or trying to save money on operational cost.  Just want the boiler to sometimes run hot and am asking what that takes. 



The ODR controls that, and it's "boost" takes too long a long time with it's small increments. 



Simple. 

SWEI

Bypassing ODR directly

Determine the OAT which will produce the water temp you want.  Check thermistor table for the correct value.  Find the nearest standard resistor value.  Buy one. Install SPDT relay and choose between ODR and setpoint.

Cliffy

simple and sweet

Thank you.



A simple resistor will do it...  (hit on head).

Ironman

The Scenario is Correct, No?

From what you've stated, I don't know how anything else could be deduced:

1. You have ODR. Its purpose is to save energy by matching supply temp to the actual load on the structure. This also produces greater comfort in the process. These are facts, though not stated by you.

2. You are using setback, even though you didn't directly say so, because you want to more rapidly warm up the heated area and the boost function is doing it in increments that are too small. That you did state and there can be no other way of interpreting that other than using setback. If I'm wrong, please show me and I'll apologize.

3. You are seeking a method to jury-rig something to get around the logic that Burnham placed in their control. Though you don't state it, that strongly implies they missed something in its design. Action speak louder than words.



What I was try to get you to see is your thinking and re-engineering attempt is flawed.



Please follow: ODR and setback are opposite approaches at reducing energy consumption. As I stated above, ODR reduces energy consumption by matching the supply water temp to the heat loss of the structure at any given o.d. temp. Greater comfort is a by-product. In fact, a properly designed and adjusted system with ODR almost doesn't need a thermostat, the logic of the control will provide just the right amount of heat. In case you doubt that, I've got one right next door that's been doing just that for weeks with no thermostat on it.



Setback, however, takes a vastly different approach. It simply turns the system off until the structure drops to a lower temp. Then, it attempts to return the structure to the higher temp when it is setup. If the setback is deep enough or long enough, there can be energy savings. Usually, not that much. But, it comes at the sacrifice of comfort. Just the opposite of ODR. This approach is counter-productive to ODR, totally.



The engineers at Burnham were more than knowledgeable enough to realize all this. They also realize that most Americans are wed to the antiquated idea that setback is the way to save and that many will attempt this even though it's fighting against the better technology of ODR. Their solution is the boost feature. It's a compromise between to waring approaches because they knew Americans would use setback. And, they're not the only manufacturer to offer it by any means. Although, most, if not all German mod/cons, do not offer it because they know it's counter-productive.



I've said all that to try to get you to see that it's your operational approach that's wrong, not the boiler's control system. Reduce or eliminate the setback and you'll have greater savings AND comfort. The boiler control doesn't need modifying.

Tim McElwain

Procedure recommended by Burnham

is as follows:



Overriding the Outdoor Reset functionality of the U.S. Boiler ESC-IQ Reset Card can be accomplished two ways. While overriding this function is going to be prohibitive to appreciating the energy savings the boiler and control has to offer, it is doable.

 

The first way involves a function the control is equipped with called "Boost". If the control sees a constant heating demand from one or any of the thermostats that has not been satisfied in a programmed time period of 20 minutes, it will begin boosting the set point temperature by ten degree increments every 20 minutes until all the heating zones are satisfied or until the boiler reaches its programmed high limit of 180 degrees. This time period can be reduced by entering programming mode on the reset option card and scrolling with the "I" button until you see "tb" on the Option Panel display. Reducing the time to a lower number will allow the boiler set point to get to 180 degrees much quicker. It is adjustable from 0 to 20 minutes.

 

The second way is to enter programming mode on the Reset Option Card and scroll with the "I" button until you see "Lt" on the Option Panel display. This is the Minimum Boiler Temperature function of the card which comes programmed for 130 degrees. Raising this closer to 180 degrees will override the Low Boiler Water Temperature function and will make at least this temperature every time it fires for heating. Again, both of these will be counterproductive to what the control has to offer but it will accomplish what you want.

 

NOTE: Jumping out terminals 3 & 4 or the DHW demand terminals is NOT advisable as the boiler will continue to maintain 180 degrees whether there is a demand from the thermostats  or not.

Cliffy

Conclusion

SWEI hit the nail on the head with an alternative sensor (resistor).



All we want to accomplish is to easily and temporarily bypass the ODR setpoint when the old folks come to visit.  Nothing more than that.   



I realize it's overriding the energy savings we enjoy, but sometimes one does what they have to.  A few hours now and then of highest temperature setting won't break the bank, and it will make some others very happy.  It's worth it.



The "boost" feature, with it's incremental time to raise the temperature

step by step, simply takes too long.  It's good for recovery, not instant results.



Appreciate the help, all of it.