I have a 14 yr old BARD 5 ton ground source unit that had some work done over the summer; cooling is fine but efficiency in heating is poor and the house is struggling to keep warm. What could cause the low efficiency? Exchanger old? TXV bad?

Blower new
Filter (both air & refrigerant) new
Charge current

Help

 

Are you having water flow from the ground loop?

Do you have a temp reading of water coming and leaving?

 

Water flow from the pump and dump system is go @ 5 GPM (restricted at the unit). I do not have temp in/out nor do I think I have anything capable of reading it.

 

Get one of those cheap weather wired station that you would stick outside to take a reading..

Take that sensor on one of the line, and tape it to and let take a reading for a few min till you see no changes in reading..

Then do the same on the next line.

 

Using what I could find, I get 56 deg in and 53 deg out. Does that sound right? What should it be?

 

First off I look for at least 3 gpm per ton in geothermal. Then regulate the flow at the unit (using the outlet valve) to obtain a temp drop/rise of 10 degrees across the water coil.

Works fine in cooling but not heat.

Might be the reversing valve not shifting all the way for heat.

Perhaps some Supco 8 oil injected into the system and work the valve back and forth will get it unstuck.

But that would requier EPA cert to do.

 

I agree with Jarrad on what he has posted.

 

Bard requires an inline 5 gpm restirictor; are they wrong?

http://www.bardhvac.com/digcat/volum...100-155(N).pdf

Model WPV-36B

Since this is an open loop system and the water coil has never been cleaned, shouldn't it be acid washed?

Thanks for the ideas

 

Have you every had the water tested????. I know here that anything that has to do with a water heat exchanger around here has to be cleaned every year . With a good acid wash of some kind. So it will work right. Any supply house will have a flow Temp control for the water . Its like the one we use on a water cooled Ac units. Look for Virginia water treatment . Also stuff made by Calgon. To use as a cleaner.

 

First, you have a 3 ton unit and not a 5.

Second, always follow the manufacturers reccomendations. They say 5 GPM give it 5 GPM. I would look for 9 GPM But I didn't build the unit so thats that.

If it's piped as is indicated in the installation manual you could acid wash it. I use about a 20% muratic acid and 80% water solution. Use a cheap Lowes submersible pump and circulate counter to the normal water flow.

 

[QUOTE][/Filter (both air & refrigerant) new
Charge current
QUOTE]

Why the new "drier" or filter in the freon line????

 

One of the repairmen was stumped why the unit was tripping on "high head" in the heating mode but after changing out some sensors, filters, etc... he figured out that the new gauges were not working right. Since the line was open, he changed the filter, blew out the system, hooked up a vac pump and then added in a new charge.

I am still not convinced that the TXV is set right.

I did cycle the reversing valve to see if it might help; no change

Having the coil flushed tomorrow and then I will report back in how the delta T improves (or not). Currently have a 3.8 degree delta T (water in versus out)

 

High head first thing exchanger "ALL THE TIME" Inside coil clean blower ok

 

It's tripping on high head because:

1. The Indoor coil is stopped up (not enough air), fan has a problem (not enough air) or filter is dirty (not enough air).

2. The strainer is stopped up (black in figure 2 - heating cycle).

3. Your right and the TXV is the problem.

Looking at the manual again and in more detail I see why Bard gets away with only 5 GPM. Water to refrigerant flow is ONLY counter flow in A/C. In heat Bard is depending on heat transfer at the indoor coil and not in the water coil (flow isn't counterflow).

I'd bet if you read the line temp before and after that strainer you'll fid a bit of a difference.

 

The saga continues:

* Acid wash of water coil complete; although it helped (1/2 degree differential improvement) it was certainly not the problem.
* Clean the air coil / evaporator as it was dirtier than it should have been
* Unit still runs all the time

Water side okay; Refrigerant side must be the issue which leads me back to the TXV. The TXV was adjusted by one of the techs last spring but he had "trouble" seeing any change so my hunch is that he screwed it up. I am getting a set of refrigerant gauges from work to see if I can't adjust the TXV so that the superheat is working properly.

I plan to balance the system based on the recommended pressures.

Any suggestions/tips on adjusting the TXV would be appreciated

 

CHANGE IT!

Since the system was installed without bleeding nitrogen, that is your problem.

Change the TXV and all filters, driers, in the refrigerant system.

AND BLEED NITROGEN when brazing!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Evacuate to 500 Microns or less!

Or else you'll end up right back here. <---PERIOD

 

The repair last time (recharge, filter/dryer) was done with N2 as well ... how exactly he did it, I don't know.

Attempted to adjust the TXV this morning, regardless of the position of the valve, the pressures remained 64 low and 175 high. The 175 high should be closer to 225 which is why (I assume) that the heating is so bad. Also, since the adjustment of the TXV did not make any difference, that is a good indication that the valve is shot??

When the repairman comes back to change the TXV, should he change anything else (filter/dryer, reversing valve, ???) since he has to tear it down anyway?

 

Any thoughts on where to purchase the expansion valve?