ReplyIf you have the manual see if it is programmes correctlyOriginally Posted by RSB
you may have the user manual but you need the installers guide
Regular Guest
Hello,
We had a Honeywell vision pro 8000 installed. The system is all electric with a heat pump and electric strip heaters. It works great with temp above around 30. When temps get down below 20 or so the heat pump never cycles off. With my old mercury switch I would just switch to electric heat when temps would go low and the system would cycle on an off like a gas furnace. With this new stat when we turn off the heat pump and go straight to electric, the system cycles on an off very erratically. At times maybe on for 20 min then off for 2 miniutes then on for 10 and off for 30 seconds and so on. Any help would be great - thanks!
Professional Member*
If you have the manual see if it is programmes correctly
you may have the user manual but you need the installers guide
Regular Guest
d-griff - wow thanks for the reply. Yes the installer and I went through manual and I have the installer's guide but I'm not sure what I can mess with. I tried a couple of setting changes but didn't make any difference. When I tried to tell the service manager about my issue they said i should keep the heatpump on full time no matter what the outside temp is and said it's cheaper like it returns 3 or 4 $ worth of heat for every 1 $ of use...huh.. Besides running 24 hours a day I figured if my electric only ran 1/3 to 1/4 of the time then it's a break even. Thanks again.
Professional Member
Your heatpump running all the time at those temps will help heat your home, and do it more cost effectively then straight heat strips. Make sure the stat is set up for allowing back up heat. If you have say 15 kw heat strips you will be using aprox. 80 amps, depending on the outdoor unit size you will be using only about 15 - 20 amps. your heat strips should be staged to come on based on the balance point of your home . Did the contractor do a load calc to check your homes heat loss to determine the balance point? Sounds like you may have a wiring problem.
Genius = The guy who can do anything...except make a living!
Professional Member*
So you had a new stat put on en existing system correct??
I have seen some problems with the new vision pros and heat pumps, You can sometimes set them up for a heat pump but sometimes it is better to set them up as conventional system with multiple stages of heat..
I have seen systems shut off/on immediately and that was a direct result of the thermostat being setup wrong..
but you are describing a slightly different problem
God Speed, Jim. We'll miss you - 2-26-23
Lower the CPH setting of the second stage heat(strip heaters)
Leave the heat pump on. It is cheaper the just the electric heaters.
Professional Member*
I agree with him.. Even tho the manual may say 9 for electric heat, bump it up to like 5, and if you find it still cycles more than you care for, then 3.
Also, don't use set back on heat pump, just set it and forget it, and if the heat pump can't keep up it will cycle the electric heat to help keep up.
Is an outdoor sensor used on this t-stat??
Regular Guest
I did change the CPH settings with no affect. I don't have an outdoor sensor installed. The stat was put on an exisiting 3 year old 4 ton Weatherking heat pump and a Payne air handler with heat strips. Not sure of the amps. So when I go to straight emergency heat should I expect it to cycle on and off like a gas furnace vs. the intermittant way it goes now. Thanks again!
God Speed, Jim. We'll miss you - 2-26-23
If you have the CPH for the heat strips set to 3, then yes on emergency heat it will cycle like a gas furnace. But your heating bill will be high. The strip heaters will use twice as much electric as the heat pump.
You can also set the second stage CPH to 2.
That will cause the the stat to keep the heaters on until set point is reached when they are used for aux heat.
Regular Guest
Not sure which CPH to mess with since there are about 6 different groups of settings. I guess what I'd really like to ask here is to find out if my system is operating correctly since they installed my new stat. So here goes:
1) In heatpump mode the house is very comfortable but when the temps drop to 25 and below the thing runs 100% of the time even when the indoor temp and stat setting are the same. Why wouldn't it cycle off for at least a little while.
2) When on straight e-heat why does the system cycle on and off erratically, like on 20 min then off 3 then on 1/2 hour then off for 15 seconds...
The service mgr at the HVAC company said it's working correctly but I wanted to double check by asking this group.
Thanks!
Regular Guest
Change the CPH for e-heat alone (emergency heat) to 3 and do the same for the aux. heat CPH setting. That way they will not cycle too rapidly. These setting are accessed through the manual in the installation manual, which is also available on the internet.
Get a digital thermoter, available anywhere these days and stick it in the outlet closest to the air handler and leave it there and "on". The exiting air should be at least fifteen degrees above the room temperature and if it is isn't the HP is probably undercharged or it's incredibly cold outside. As the outside temperature drops a HP provides less heat and if it cannot actually keep the temperature up the auxilary heat will kick in, adding to the duct output temperature. You can manually kick in th auxiliary heat by raising the temperature on the t-stat a few degrees and should see a temperature rise on the duct when that happens and if that does not happen the t-stat is not set up correctly.
Professional Member*
When the outdoor temperature drops to 25 it would be normal for the HP to run constant.
Leave it run and when the Tstat is set for lets say 70 degrees and outdoor temp is low look for the aux heat indicator to see if it is on.
The Tstat is designed to maintain a "0" degree" droop. and the HP might be delivering it. If the system charge is correct it is cheaper to let it run continuous and cycle aux as needed than to switch it to EH.
Regular Guest
The install manual is a little confusing to me trying to determine which settings to try. I do see a em heat setting but it says 3 = cpy for hot water or fossil fuel whereas i would guess mine is a 9 which equals electric heat. So should it still be a 3? Also is auxilary heat the same as 2nd stage heat? If so it has the same options as e-heat above.
Thanks again Carry On!
Regular Guest
Forget that the installation manual says that. It doesn't have to be set to 9. Set both to 3. Also check that CPH for the compressor stage is 3, which recommended. The number merely determines the effective sensitivity of the t-stat in each mode. I've found that 3 is a good number. For instance, the 3for cooling stages meaning that the AC will go on and off three times per hour. In effect, the number changes the stats. sensitivity (to keep it simple here).
My electric was cycling very rapidly when the installer put the stat in and left the setting on 9 and walked out the door check in hand. I set it to 3 which is perfect when I saw that it cycling rapidly. He was clueless when I told him; thought that electric heat had to be set to 9.
Regular Guest
Out of the 6 or so setting in the manual I think only a few of mine are available depending on the System selection which is 2 heat / 1 cool. So when I get home tonight I'll see what options i have for CPH. Do you think I should set them all to 3? Thanks!!!
Regular Guest
When you enter the setup for each setting, you can scroll through the numbers that are available. 3 is a good start. I think all the numbers from 1 to 9 or 14 (depending on what is being set up) will be available. If you don't have 3, use 4. You can experiment with numbers.
You'll notice that several of the pros below also like 3. 4 might be just as good. Either one will cut down the cycling significantly compared to 9. I do not know if the changes are proportional. I tried 3 and liked it for the electric heat settings.
God Speed, Jim. We'll miss you - 2-26-23
Set them all to 3. Try it for a couple days, not just for a night.
Its common for the digitals to be set at a temp, the display to show that the room is at that temp, and the unit keeps running. It helps to prevent short cycling.
Regular Guest
Success - 3 worked great. It especially let the electric heat cycle consistantly. At about 15* last night the on heatpump/aux it ran full time but on electric it would run on about 20 min then off about 10. Normal? Still cheaper on heatpump?
Do you think I should send a letter or call the HVAC company and tell their service mgr (who basically said it was fine) to subsribe to your site. It might help them!
Thanks for all of the help!
Regular Guest
That's a good setting for all electric heat.
As long as the heat pump can maintain the temperature evening staying on you want you are heating for less that using all electric or aux. heat.
But if the heat pump cannot maintain the temperature because it's very cold or the house is drafty, the aux. heat should come on (indicated on the t-stat.). If the aux. heat does not go on enough each hour, raise the aux. heat number until you are statisfied that the HP and aux. heat can keep the place warm. You will not hear the aux. heat go on and off more frequently because it will only go on when the HP and blower are already operating. That is, you won't notice the rapid cycle you found but now solved with all electric heat, which is "emergency" heat, used only when the HP is inoperative.
I wouldn't bother explaining your self study and tune up to the tech. Mine didn't care and in fact doubted I was correct.
God Speed, Jim. We'll miss you - 2-26-23
Glad you like the operation of the 3 CPH setting.
You might want to send a letter telling that company we told you here.
And yes, suggest they come here.
They may not take the suggestion, but atleast you gave then the info were to find out solutions to problems they may run into in the future.
Posting Permissions