UPS for Boiler

[mkgrady]

I do a lot of work with a heating contractor that has asked me to install a UPS in line with his gas boiler at his house. He wants this because during a recent power outage his generator was feeding power to the boiler burner and on more than one occasion the boiler quit and had to be reset. I don't know anything about the burner except it is fairly new and very effecient. He wants the burner to get cleaner power than his generator will deliver. I would suspect the most the burner and circulator pumps would draw would be 4-5 amps. The circp pumps are very small. I imagine I have to consider starting current on the burner motor.

I don't have any idea where to begin to buy or even size a UPS for this. The only experience I have with UPS's are the little ones that plug in for a desktop computer or commercial ones that fill a large room that I did not select. Any feedback would be appreciated.

 

[Strathead]

I do a lot of work with a heating contractor that has asked me to install a UPS in line with his gas boiler at his house. He wants this because during a recent power outage his generator was feeding power to the boiler burner and on more than one occasion the boiler quit and had to be reset. I don't know anything about the burner except it is fairly new and very effecient. He wants the burner to get cleaner power than his generator will deliver. I would suspect the most the burner and circulator pumps would draw would be 4-5 amps. The circp pumps are very small. I imagine I have to consider starting current on the burner motor.

I don't have any idea where to begin to buy or even size a UPS for this. The only experience I have with UPS's are the little ones that plug in for a desktop computer or commercial ones that fill a large room that I did not select. Any feedback would be appreciated.

Perhaps you can separate the motor from the control circuit and only UPS to control circuit.

 

[don_resqcapt19]

Even if you can separate the controls from the motor loads, many electronic furnace control systems will not like the output of a cheap UPS.

 

[mkgrady]

Perhaps you can separate the motor from the control circuit and only UPS to control circuit.

I would only do that if I had to. This customer doesn't care what it costs, I just don't know how to size what to get

 

[mkgrady]

Even if you can separate the controls from the motor loads, many electronic furnace control systems will not like the output of a cheap UPS.

I wasn't thinking cheap. I will pay whatever is needed to do this right

 

[GoldDigger]

I would only do that if I had to. This customer doesn't care what it costs, I just don't know how to size what to get

If the burner runs from 120 volt single phase at less than 15 amps, just drive the burner through a Kill-a-Watt (TM) meter to collect peak power and average power usage numbers over a representative period of time. The only thing it will not give you is the motor starting surge. Fluke, among others, makes a good meter for that.

 

[jim dungar]

It sounds like the Owner wants a 'power improvement' device, not a 'power backup' one. Very few small UPS's actually provide power quality improvement.

You might want to look into what we used to call a Power Conditioner. These transformers provided constant voltage and noise filtering.

 

[mkgrady]

If the burner runs from 120 volt single phase at less than 15 amps, just drive the burner through a Kill-a-Watt (TM) meter to collect peak power and average power usage numbers over a representative period of time. The only thing it will not give you is the motor starting surge. Fluke, among others, makes a good meter for that.

Not sure what to do with that info. I would think tuning on the burner with all zones calling would give me the same info with an amprobe. Let's say I find the FLA to be 7 amps or 840 watts. How would I go about selecting a UPS for that?

 

[GoldDigger]

Not sure what to do with that info. I would think tuning on the burner with all zones calling would give me the same info with an amprobe. Let's say I find the FLA to be 7 amps or 840 watts. How would I go about selecting a UPS for that?

For selecting the output capacity of the UPS you need to know the VA consumed. But for sizing the battery and looking at run time you need to know the actual watts. Your Amprobe will not give you the PF information. But I agree with Jim that just a UPS, even one which delivers clean sine wave output, will not have the run time that he will need and will not give any advantage when he is running the generator anyway.
An alternative to a power conditioner would be a dual-conversion UPS in which the output is always driven by an inverter, with the DC to the inverter coming either from the AC line or from batteries. Unlike a power conditioner, that would let him stop the generator from time to time without killing the boiler. This is the sort of equipment designed for servers rather than home computers and is priced accordingly.

The basic design decision on a UPS is threefold:
1. Can it deliver the maximum continuous power output needed? Look a the VA and watts of the load.
2. Can it deliver any motor starting surge?
3. How long can it deliver the average power output needed? Look at the watts consumed and compare to the watt-hour capacity of the batteries to find the run time.
A UPS will typically specify the run time at various load levels rather than watt-hour capacity, and for above ~25% load the relation is close to linear. If a UPS can deliver 1Kw for 1 hour, and you need 500 watts average, you will have a run time of 2 hours.

 

[GoldDigger]

Not sure what to do with that info. I would think tuning on the burner with all zones calling would give me the same info with an amprobe. Let's say I find the FLA to be 7 amps or 840 watts. How would I go about selecting a UPS for that?

For an intermittent load, like a burner which cycles or a refrigerator, the total-over-time capability of the Kill-a-Watt is a big advantage. It saves you the work of timing the cycles over a 24 hour period to calculate the average load!
One caution: Although it will read watts, VA and PF and do a pretty good job for displacement power factor loads like motors, it can give wildly wrong numbers for non-linear loads like LEDs and CFLs which have a poor distortion power factor.

 

[mkgrady]

It sounds like the Owner wants a 'power improvement' device, not a 'power backup' one. Very few small UPS's actually provide power quality improvement.

You might want to look into what we used to call a Power Conditioner. These transformers provided constant voltage and noise filtering.

Thanks, that sounds like just what is needed.

 

[mkgrady]

For selecting the output capacity of the UPS you need to know the VA consumed. But for sizing the battery and looking at run time you need to know the actual watts. Your Amprobe will not give you the PF information. But I agree with Jim that just a UPS, even one which delivers clean sine wave output, will not have the run time that he will need and will not give any advantage when he is running the generator anyway.
An alternative to a power conditioner would be a dual-conversion UPS in which the output is always driven by an inverter, with the DC to the inverter coming either from the AC line or from batteries. Unlike a power conditioner, that would let him stop the generator from time to time without killing the boiler. This is the sort of equipment designed for servers rather than home computers and is priced accordingly.

The basic design decision on a UPS is threefold:
1. Can it deliver the maximum continuous power output needed? Look a the VA and watts of the load.
2. Can it deliver any motor starting surge?
3. How long can it deliver the average power output needed? Look at the watts consumed and compare to the watt-hour capacity of the batteries to find the run time.
A UPS will typically specify the run time at various load levels rather than watt-hour capacity, and for above ~25% load the relation is close to linear. If a UPS can deliver 1Kw for 1 hour, and you need 500 watts average, you will have a run time of 2 hours.

So much of what you say would seem to matter except that he never looses power. He has a standby generator. I will plan to look for a power conditioner as Jim suggests. Not that I know anything about them either.

 

[mkgrady]

Thanks, that sounds like just what is needed.

All the Power Conditioners I am finding are plug-in and plug-out. I probably need additional search words.

 

[unytko]

Problem with generator(even stand-by type) is that is has "power brake" for about 3-5 seconds (depending on the brand) and some of the new
HTech. equipment must be reset manually to get it back in order. I recently installed UPS for my brother to test it and it works fine.

His problem was with Crestron System and thermostats, each time there was power interruption system would never recover completely leaving thermostats in off mode.


http://www.furmansound.com/product.php?div=02&id=F1500-UPS_CE

 

[jim dungar]

All the Power Conditioners I am finding are plug-in and plug-out. I probably need additional search words.

Try 'constant voltage' or ferroresonant transformer.
http://www.acmepowerdist.com/power-conditioning.htm

 

[brian john]

I had a call from a generator contractor they had sold a generator to a home owner for the house's elevator. After installation it was discovered the elevator would not operate while on generator. We separated the elevator controls from the motor and provided a true on line UPS and this resolved the problem.

 

[mkgrady]

I had a call from a generator contractor they had sold a generator to a home owner for the house's elevator. After installation it was discovered the elevator would not operate while on generator. We separated the elevator controls from the motor and provided a true on line UPS and this resolved the problem.

What does "True on line UPS" mean

 

[brian john]

True on Line UPS

Double conversion - AC to DC to AC with a 60 hertz sine wave, not a step wave.

http://www.emersonnetworkpower.com/en-US/Products/ACPower/RackmountUPS/Pages/liebertgxt3onlineups5003000va.aspx

From Liebert

1. 1. A. Normal - In normal operation incoming AC power shall be fed to the input power factor corrected (PFC) rectifier that converts the AC power to DC power for the inverter. In this mode, power shall also be derived from utility power for the battery charger. The inverter shall derive DC power from either the PFC rectifier or the battery and regenerate filtered and regulated AC sinewave power for the connected load. The battery shall be charged once the unit is connected to utility power, regardless of whether the UPS is ON or OFF. In the event of a utility outage or severe abnormality (sag or swell), the inverter shall support the connected load from battery power until the battery is discharged or the utility returns, whichever occurs first.
   2. B. Battery - Upon failure of utility / mains AC power, the critical AC load shall be supplied by the inverter, which obtains power from the battery. There shall be no interruption in power to the critical load upon failure or restoration of the utility / mains AC source.
   3. C. Recharge - Upon restoration of utility / mains AC power, after a utility / mains AC power outage, the input converter shall automatically restart and assume supplying power to the inverter and the battery charger to recharge the battery.
   4. D. Automatic Restart - Upon restoration of utility / mains AC power, after a utility / mains AC power outage and complete battery discharge, the UPS shall automatically restart and assume supplying power to the critical load and the battery charger automatically recharges the battery. This feature shall be capable of being disabled by the user.
   5. E. Bypass - The integral bypass shall perform an automatic transfer of the critical AC load from the inverter to the bypass source, in the event of an overload, PFC failure, overtemperature, DC bus overvoltage or inverter failure conditions.

 

[mkgrady]

Thank you Brian John

 

[kwired]

Not sure what to do with that info. I would think tuning on the burner with all zones calling would give me the same info with an amprobe. Let's say I find the FLA to be 7 amps or 840 watts. How would I go about selecting a UPS for that?

Remember when running on utility power you will not have the voltage sags and surges you will see when running on a generator. Even relatively small loads that do not effect utility voltage when switched on or off will possibly have some impact on generator voltage. A 100 watt load is about 1.25% of capacity of a 8000 watt generator, it will result in a relatively small change in system voltage when switched, but think about how much smaller percentage of full load it is to a utility owned generator that puts out several megawatts of power, it will not be easy to measure any voltage change in the generator when switching such a small load.

Your clean power problems are because of the voltage fluctuations whenever load on the generator changes. That is why it was mentioned to isolate the pumps from the main controls, as the pumps will handle voltage fluctuations pretty well, but the controls will like to see more constant voltage. Something with battery backup and regulated to put out constant voltage will give greater results, and will not cost as much if it doesn't have to supply the pumps. A few hundred watts often makes a big difference in cost of this kind of equipment. Simple 12 volt inverter like is used for automotive and recreation will give you pretty clean power - if it doesn't have the surging motors, and if it is only driving the controls would not need to be very high of a capacity unit either. You still need something with battery if you can't have any loss of voltage even if it is only once when power transfers from utility to standby. If you can deal with getting past transfer then your options change some.