Waterfurnace E060 Low pressure lock out-Need help.
I have a Waterfurnace E060TL111NBDSSA, 5 ton closed loop Geo Thermal system. It was installed in late 2004 and put into service early 2005. This unit has IntelliZone installed and three thermostats.
It has worked fine till recently when it began locking out with a "Low pressure" error.
So far we have added water to the loop as pressure there was low. Loop pressure is fine now.
This is what has been done to troubleshoot the low pressure lock out problem.
1. Gauges were put on the high and low side. Both high and low pressures were ideal with now low side pressure problems.
2. To eliminate the low pressure switch, it was shorted. WFI manuals say the low pressure switch has to remain open for 30 seconds before lock out.
3. Ohmed out the current sensor. It is at 140megohms. Not sure if this correct or not? Seemed really high to me. So help here is requested.
Here is a little more history. This unit cycles between the high and low side of the compressor frequently. If you have a Y1 call, the compressor starts on low. If it progresses to a Y2 call, the compressor immediately shuts down, waits a minute, then starts the high side of the compressor. This seems normal. Compressor stays on the high side till the Y2 condition is satisfied. Once the Y2 turns to Y1, the compressor immediately shuts down, waits a minute and starts the compressor on the low side till the Y1 is satisifed and the compressor shuts off. Is it correct for the compressor to switch from high to low when the call goes from Y2 to Y1? Just seems like a lot of starting and stopping by the compressor. I'd prefer it stay on the high side till the Y1 condition is satisfied, but I don't see a switch for this type of operation.
I'm wondering if the low side contactor might be burnt enough to increase current at start up to trip the current sensor, thus locking it out on Low pressure? The problem seems to occur when the unit is running on the high side, satisfies the Y2 call, shuts down and restarts on the low side of the compressor.
So far, we have been able to get it back up and running by cutting the power for 10 seconds and turning it back on. The problem started out with a frequency of two weeks and now it is happening twice in a 24 hour period.
A couple things I'd like to know, can the current sensor be tested or bypassed to see if it a source of the trouble? What is the ohms reading of a new current sensor? Is the Hi/Low compressor cycling when going from a Y2 call to a Y1 call correct? Any other details or ideas are appreciated.
Thanks in advance for your help!
In cooling mode, a Low Pressure lock out should be from low air flow or low refrigerant. Make sure your filter is clean, the blower is operating normally and the zone dampers are opening properly.
As far as the unit cycling goes... You need an upgraded control board. The newer boards will allow you to set it to finish on second stage. This will cut down the amount of times the unit cycles.
Thanks for your input. Here's a little more detail regarding the points you brought up.
The gauges confirmed the refrigerant levels are correct for the high and low sides. Air flow seems great as the filter is new and the same type used all along. Just to be safe, I vacuumed the coil and flow through the coil is real good. Air coming out the vents seems strong for the blower speed. I will double check to be sure dampers are working properly, but my gut says they are. Good to check though.
One question, how does the system determine the filter/coil is clogged and giving poor air flow? Is it drag or increased current on the blower? Just curious.
What's the general cost for an upgraded control board as it just seems logical to have less hi/low compressor switching for longevity of the entire system.
Unfortunately, without being present at the unit, we are unable to determine what is causing your unit to lock out on low pressure. We would suggest having your contractor contact our technical support staff for further assistance. We are more than happy to work with you and your contractor to assist in facilitating a resolution.
WaterFurnace International, Inc.
A couple things I'd like to know, can the current sensor be tested or bypassed to see if it a source of the trouble?
You can bypass the current sensor. If low pressure goes away and unit is not cooling while fan is running then the compressor is off on overload.
I would use caution compressor cycling on overload could be It's demise
What is the ohms reading of a new current sensor?
Hard to diagnose with OHM meter It's open unless current is present
Is the Hi/Low compressor cycling when going from a Y2 call to a Y1 call correct?
Yes assuming it's a Bristol compressor.
Things are more complicated because the fan is controlled by the intellizone.
Otherwise you could lock it in high speed. You would have to bypass intellizone to do that.
Most likely one of 3 things
relay and capacitor
The Bristol is no longer available
Replaced by the Copeland 2 step scroll
I wish you luck
Reply to Teeball 57 in Blue font
I guess the only way to upgrade the Premier control board, 17P513-03 rev C, is to replace it or is an upgrade available? It would be nice to have the "finish on high" feature to limit compressor cycling. Thanks,
Originally Posted by teeball57
Sorry...no upgrade, just a replacement board.
I thought that might be the way it would go......
Thanks Bergy. The good news in it all is the unit has a 10 year parts warranty and next plans are to replace the Premier Control board. Hopefully the only rev available is the updated version with the "Finish in High" option.
Originally Posted by Bergy
Both high and low 40A relay contacts were pitted. I cleaned them up and they are working fine, but the problem still occurs. Are the relay contacts replaceable or do you replace the whole relay?
The relay and capacitor are part of the compressor start circuit I would replace them before replacing compressor. You will have to get them from WFI The contactors are another matter.
As I said before you have Intellizone which controls the fan if you lock the compressor in high speed and Intellizone drops the fan to low speed your going to have a problem. Think about that!
For diagnostics you could open the dampers and disconnect Intellizone. Run one stat directly to the unit and reconnect the fan to the unit.
To lock in high speed disconnect the Y1 wire @ the board.
Board replacement will not do you any good at this point
If compressor is the problem you will get a new board with the replacement kit.
Response to Teeball57
Originally Posted by teeball57
Curious why you say a new control board won't do any good? Is it because the control board is being driven by the Intellizone board?
That is correct. Intellizone is controlling the fan separately, based on therostat input, if you lock it in high speed compressor on main board the Intellizone is not seeing that and will revert to low fan if that is what the thermostats call for.
A new style scroll will shift to high speed on the "fly" but the Intellizone still calls the fan speed according to thermostat input.
Simply put you cannot lock in high speed compressor with Intellizone.
One note: if you have the new style two step scroll you would have no need to lock it in high speed as it will shift from low to high without restarting.
I wouldn't hesitate on this one, especially with the warranty. New compressor and board kit.