Lunaire AC

larryeddington · Post by **larryeddington** » Sun Aug 05, 2012 10:43 pm

I think what he is describing is insulating buildup of slime mold, scaling, dog hair or just plain crude on the evaporator coil which is the one that gets cold and extracts heat from the air passing through it. Definitely will reduce efficiency. Onversly poor condensing water flow through restrictions or buildup on the interior of the condesing heatexchanger will give similiar results.

Again IMO water temperature is not the issue here. He also correct regarding humidity, an AC does two things cools the air and dehumidifies it. Dry air feels much cooler to the human. In fact sometimes persons over AC a location which does not remove enough moisture so you have clammy cold air that does not cool you as well.

Sounds like you have an AC tech that understands HVAC.

prowlersfish · Post by **prowlersfish** » Sun Aug 05, 2012 11:07 pm

Both water temp air inlet temp and humidity factory in the AC performance / outlet temp. .

larryeddington · Post by **larryeddington** » Mon Aug 06, 2012 10:46 am

IMO I stand on water temperature not being the culprit behind this issue.

prowlersfish · Post by **prowlersfish** » Mon Aug 06, 2012 12:07 pm

larryeddington wrote:IMO I stand on water temperature not being the culprit behind this issue.

Just saying its a factor in cooling ,if you have one look at the chart in the cruse air book . when charging it must also be known to to charge properly as it effects pressures .

larryeddington · Post by **larryeddington** » Mon Aug 06, 2012 12:48 pm

Correct, you must know water temp to set the charge correctly, whether water cooled as is in boats or air cooled as in most home AC's. It is a parameter but should not make it not perform if charged correctly and the condensing medium is not too cold nor way too hot. 90 deg water should not be too hot if flow is adequate. IMO

tsawyer · Post by **tsawyer** » Sat Aug 18, 2012 8:07 pm

Finally got the a/c tech out to recharge the system.

Cost me $85 service call + $30 for the gas and took him about an hour. He said it was a real pain getting to the fill.

It seemed cooler last night, but the thermostat indicated it was much cooler in the cabin than I think it was. The compressor kept turning off when it got to my set temp, which again I don't think was right.

I took the intake cover off a bit ago and he put the temp sensor behind the filter and up against the unit. I don't think it goes there, so I moved in to the front side of the filter so it can get a real cabin temp.

I'll see how that runs tomorrow.

What did I learn? Don't take the last appt on Friday!

aaronbocknek · Post by **aaronbocknek** » Sun Aug 19, 2012 4:11 am

i think the techs complaint about access to the unit is weak. if he does this for a living, then he should KNOW that many a boat manufacturer crams as much equipment into a small area. why he even mentioned that is beyond me. he should have kept his mouth shut. my two cents this morning.

prowlersfish · Post by **prowlersfish** » Sun Aug 19, 2012 8:41 am

If the tech was just explaning that the unit was hard to get to and it took longer to get to , thats fine . a job may take longer on one boat then another boat . the longer it takes the more it costs .

A $85 charge is not bad IMO .

As to how well the work was done , lets see how it cools . The temp probe was in the correct place , At least that were mine are .

aaronbocknek · Post by **aaronbocknek** » Sun Aug 19, 2012 9:20 am

prowlersfish wrote:If the tech was just explaning that the unit was hard to get to and it took longer to get to , thats fine . a job may take longer on one boat then another boat . the longer it takes the more it costs .

A $85 charge is not bad IMO .

As to how well the work was done , lets see how it cools . The temp probe was in the correct place , At least that were mine are .

++1

tsawyer · Post by **tsawyer** » Sun Aug 19, 2012 10:03 am

prowlersfish wrote: The temp probe was in the correct place , At least that were mine are .

Your temp probe is between the filter and up against the unit?

It seems to me the metal of the cooling unit is going to be much cooler than if the temp probe is on the front side of the filter.

It was on the front side when I took out the filter and he moved it.

I guess I'll see how it handles cooling today.

prowlersfish · Post by **prowlersfish** » Sun Aug 19, 2012 11:11 am

I believe he put it back were it belongs , But i will re check mine when I go to the boat to day . For what its worth my window units at the house also have the probe on the coils .

larryeddington · Post by **larryeddington** » Sun Aug 19, 2012 11:13 am

I agree with Aaron, negative comments are not part of service work, just fix the problem or tell me you cannot, not how hard it is as that is what the mech does for a living and I do not feel sorry for him.

Now on to temps, once the inside air has cooled reasonably one should get at least a 20 degree or more drop between return air and discharge air. Some stated correctly just mesure air not temp of heat exchanger metal. If you are getting 20 to 25 degree temp differental it is performing as it should. One issue I can see particularly in boats is humidity a very important part of airconditioning. The cooled area needs to be tight engough for the AC to remove the humidity, dry air feels cooler to humans.

prowlersfish · Post by **prowlersfish** » Sun Aug 19, 2012 11:40 am

Complaining yes is out place sure ,but telling some one the unit is hard to get to and will take longer is fine . thats why one boat may cost $100 to do a job and another $300 to do the same job.

BTW did your tech check the sea water temp when charging ? Its a major factor in the pressure reading . Head pressure is arround 110 psi @ 50 degree water and about 210 psi @ 90 degree water . this for R22 systems .

RWS · Post by **RWS** » Sun Aug 19, 2012 12:00 pm

i had an AC tech try to take advantage of me.

He sole me the new unit

then LIED about the problems I was having, just so he would not have to remove it as it was leaking freon.

I proved my point after investing in an infrared temp sensor - thermometer

With this device you can pinpoint numrous problems and take the temp of the hot raw water water exiting the boat.

It's a great troubleshooting tool for well under a boat buck.

RWS

larryeddington · Post by **larryeddington** » Sun Aug 19, 2012 12:56 pm

That was how I got into the HVAC business in the 80's. I had a "professional tech" totally screw up the job and screw me. I figured I could do better. Bought the books studied them and went into business for the next 7 years and licensed by Texas. When I made an error and all will at some time I ate it rather than push it to customer and lie.

One of the biggest quotes is the tech that says I can spend a bunch of your money looking for the leas, as it is slow, it would be cheaper to fill with refrigerant and do it again next year. Bull, a system should not leak, we are not talking about tires here but a highly technically designed engineered system. Fix it is what should be done.

There a lot of yahoo's that call themselves techs.

Also on setting a charge the unit if self contained can be charged with the amount of refrigerant on its plate without needing water temperature. If it is a split system you would need to know water temp and have a charging chart to set the proper "super heat" so system is correctly charged. Many "tech's" do not even understand superheat.

HVAC is really very simple in function, it is the controls that can get someone lost.