I had an NDV049A111CTR installed 3 weeks ago that replaced an old FHP (3.5 ton I think) that shot craps after 8 years. Not sure what model it was though. The original loop and ductwork remained the same except for some modification to the return air duct at the furnace. The thermostat was replaced with a programmable WaterFurnace stat. I have a water heater and storage tank that were also reused and hooked up to the new furnace using new copper pipes. I have a couple questions regarding this new unit. 1. The furnace will run 35 to 40 minutes every hour even though the outside temperature is in the mid teens. It is in 1st stage almost all the time so I am wondering if this is possibly just normal operation? The FHP never seemed to run this much. 2. The unit is located in the basement and makes an annoying hum/vibration that can be heard easily throughout the house upstairs. It is much less noticable near the unit. The noise is also much more prominent in the 1st stage of operation. If running in 2nd stage it is a lot quieter. Is this normal? I used a cheap thermometer and the air entering the unit is 69 degrees and the air exiting the unit is 86 degrees when running in stage 1 after about 20 minutes. I had the installer, whom I have been pleased with, return to check the unit and they say all is fine and operating properly. I was not home but the technicians work order noted the following - Temperature drop in loop 9 degrees. Check airflow, temp rise at coil 29 degrees. Checked desuperheater operation.Checked unit amp draw. Check blower speeds. Unit working ok. I am still concerned however with the run time and annoying noise or vibration. Any insight or suggestions would be much appreciated.
The unit you had before was likely a single stage unit. The unit will run longer in first stage than you are used to. However it is operating at a much higher efficiency than if it ran a lot in second stage. This is normal and is good. The vibration is coming from the heat pump itself or the flow center. Both should be mounted on foam or other anti vibration pad and needs to be continuous. Based on your description I suspect the flow center is creating the vibration. Not everyone puts the anti vibration pad under the flow center, but I now do it every time because I have had problems with vibration noise. You should also make sure your duct work is sealed up with mastic, especially where it is in unconditioned space. Based on the temperatures you and the service person measured there is a significant loss of heat between the unit and the outlet which indicates lack of insulation or significant duct work in space as cold as the outside (attic or garage). I generally keep ducts in conditioned space and when I have to place the ducts into an attic I have them buried under cellulose blown in insulation to 10 inches above the top of the duct to prevent heat loss/gain after they are sealed with mastic and have a vapor barrier duct wrap insulation. Lack of air sealing and insulation as I outlined can have as much as 40% of the energy lost to the attic. The "standard" methods of sealing (duct tape, metal or cloth) and insulating of ducts is not sufficient to maintain the high efficiency of the excellent unit you have just installed.
Geogreen, It is common to see longer run times with extreme weather conditions. Could you provide the model number of your thermostat so that we may look into your inquiry further? Unfortunately, noise is very difficult to resolve over the internet. If your contractor is unable to resolve the noise issue, please have them contact our technical support staff to discuss the nature of the noise. They will be able to offer suggestions and work with your contractor to find a resolution.
Lloyd, Thanks for the reply. I appreciate your insight and feedback. As far as the FHP it was a single stage unit. The ductwork is all located in the basement and is conditioned with the rest of the house. I was also reading the temp directly at the top of the furnace where it exits the unit so would not expect there to be much temp loss. I will make sure all the ductwork is sealed as you suggest however. I do believe the WaterFurnace is an excellent unit and that the installing dealer is very qualified and reliable. Just wanting to get some opinions/advice from the experts on this sight since the noise problem has not been resolved yet. WF, Thanks for the reply as well. The thermostat is a TP32U03. Right now it is set on 70 degrees with no setback. I think I am beginning to understand the 2 stage WaterFurnace, when in 1st stage, will by design run longer but more efficiently than the old FHP single speed. Is this correct? Just don't want to get shocked by a$400 heating bill compared to approximately $100 with the old FHP.
Geogreen, The difference in your temp measurement can come from using a different thermometer. Measure the return duct temp and then using the same thermometer measure the supply duct temp. The difference in temp is more important than the actual and when combined with actual air flow rates is useful for evaluating performance. As for the noise, what is the unit sitting on and where and how is the flow center (the box with the circulators connected to the ground loop) mounted?
Thanks for the feedback Lloyd and it is much appreciated! The unit is sitting on the same plastic base that the FHP unit used. It is about 3'x3' and 1 1/2" thick. The flow center is mounted on a wall next to the unit where the old flow center was as well. I bought a new thermometer and used it to get readings from my unit. Not that it probably matters but I did an ice bath test on the thermometer and it read 32.3 degrees. I got the following results using the same thermometer for the air readings as well as the loop temps. Stage 1 operation after 15 minutes run time EWT 39.7 LWT 35.4 EAT 68.7 LAT 90.5 Fan speed is set at 1350 according to the dip switch Stage 2 operation after 15 minutes run time EWT 38 LWT 32.3 EAT 69.3 LAT 95.7 Fan speed 1550 according to the dip switch Do these readings seem normal or ok? There is a switch for the hot water option on the unit but I did not shut this off when I was getting the temp readings so I suppose this likely affected my LAT readings. I am not real comfortable with the loop temperature and hope this does not become a problem.When it was originally installed 8 years ago there were 4 trenches dug and each was about 100 yards long and 5' deep. Each trench had 1 loop buried in it but do not know much more than that about the loop. It has been cold here the last several weeks with the temperature staying below freezing most of the time and in the low teens through the night. I will remain optimistic the loop is ok. Thanks again for any insight.
Good move doing an ice bath test on ther thermometer, although using it just to measure differentials makes it less important. Given that the noise changes with stage, I'm not inclined to look to the flow center unless a second pump comes on with high stage, and that is not commonly done. Ensure shipping bolt(s) were removed from compressor mounting base - this is an easy error and makes a huge difference with noise and vibration. Some units have a harder-to-see 2nd shipping bolt. IF ductwork is ALL located within conditioned space don't drive yourself nuts hunting down every last leak - it simply isn't necessary. I use the closed cell foam pads supplied by WF under compressor units. Others have as good or better results using blue / pink XPF board. A hard plastic base won't work as well. Your temperature splits look great. It is fine for the thing to loaf along in low gear for an hour or more at a time. EWT in upper 30s is fine for your location this time of year - I trust there ia antifreeze in the loop... One thing to note is that since it reads as though you have a proper DSH install (dedicated unpowered buffer tank for DSH recovery), leaving air temp WILL vary measurably depending on the state of the tank. Expect higher LAT if unit has been running several hours and no one has used hot water. OTOH, if the buffer has been chilled by new cold water owing to recent heavy hot water use, heat diversion will be higher. Per WF tables, diversion is 15% for an 049, and that is based upon 90*F water in the buffer. If the buffer is only 50*F, diversion could approach 25%, reducing LAT by 5+ degrees.
Geogreen, I agree with Engineer that the temperature numbers are in line. The more efficient a unit is, the higher the COP, the more heat energy the unit takes out of the ground. Your new unit is more efficient than your old one, but the loop temperature numbers are good for this time of year with a hard winter. Checking the shipping bolts is good, the Installation and Operation Manual will tell you where they are. Another thing to check is the ductwork connection to the unit, are the metal duct mains installed with a canvas collar? Some contractors use short sections of flex duct, but the important thing is to have vibration isolation on the ductwork where it connects. The metal duct is a great conductor of vibration and the vibration will shoot right along the length and if it is touching framing members will conduct the vibration into the framing.
Thanks! I certainly value the feedback and appreciate the fact that you all take the time to share your expert knowledge with folks such as myself. Kudos to you both! I figured the accuracy of the thermometer was not as important since I was looking for the differentials. I mentioned it since I was a little concerned that the loop temp might be too low and am glad to hear it is probably ok. Thanks to your feedback I am MUCH more comfortable that everything is ok with my install. I do know the loop has antifreeze in the mixture but not sure what was used. There were several empty 5 gallon buckets in my basement when the original FHP was installed...but that was 8 years ago and I have trouble remembering yesterday sometimes. The DSH is installed that feeds an unpowered buffer tank that then feeds the powered tank. Now it makes sense why some of the readings I had previously taken varied somewhat since my use of hot water and timing of readings will have a direct impact. I have 2 teenage daughters and trust me they know how to use hot water! I did check and the shipping bolt was removed from the compressor mounting plate and according to the install manual there was only one on my unit There is also a canvas connector on both the supply and return ducts where they tie into the main trunk. I will work with the installer on possibly changing the pad and checking the DSH. I am confident there is a resolution for the pesky vibration noise. Thanks again fo all the response and help!
Geogreen, At the time of purchase, your contractor should have performed a WaterFurnace Energy Analysis, which would have shown the difference in savings between the WaterFurnace and Florida Heat Pump. If you did not receive a copy of the Energy Analysis, we would suggest you contact the installing contractor to discuss obtaining a copy.
Thanks WF. I will ask about the WaterFurnace Energy Analysis. Can you tell me what is involved in getting it completed?
Geogreen, The WaterFurnace Energy Analysis taking into account factors such as building heating and cooling loads, set temperature for the thermostat, balance point for auxiliary heating, etc. From this information, your contractor can calculate the estimated operating cost based upon using the average weather data from the previous 20 year history.
