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Spence

Joined on April 16, 2013

Last Post on September 1, 2014

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Venting

@ September 1, 2014 9:27 AM in Code or Best Practice for connecting 2-appliances to Chimney Liner

Advice on sizing without knowing the common vent height, appliance connector rise, length of connector, and BTUH of appliances; how is this possible?

Testing Opened System

@ August 25, 2014 6:42 PM in AC Question?

R-410A oil is a sponge, if that hints at what you're up against. The sections that were open to the atmosphere will have to be purged with nitrogen, then triple evacuated with more nitro in between. You most likely will never get out all of the moisture; have your factory tech rep recommend an oversized liquid line drier as well.

Since you're most likely able to float a boat with the moisture, try to get your triple evacuation to 300 microns or below. If you can't, here's a guideline: after each evac, change your pump oil. If you can get to 500 microns, for example, and you don't rise over 750 within a minute or two, you're probably at the best you can get under the circumstances.

Please understand this is not without risk. The system has to be hooked up to do this, or you'll be doing 9 evacuations. And the system may not run or live long anyway. If it does run😢 (that darned yellow guy again), keep your eye on that drier!

DO NOT use the stupid vacuum section on your compound gauge! Use a quality micron gauge. Best of luck!

Drain Line

@ August 23, 2014 10:33 AM in condensate drain ?

I wonder why they did not install the secondary.

Drain

@ August 21, 2014 6:19 AM in condensate drain ?

If the blower is upstream from the coil you should have an air relief. If the blower is downstream there should be a trap. The 3/4" minimum condensate line should have a 1/4"/ft. drop toward the drain.

You're holding water. It's not the equipment design, unless the factory missed something we can't see. Something in the installation; coil position perhaps. You're also making lots of water, so I would calculate your air flow to make sure you don't have restrictions that make more water than the drain can handle. The photo makes your could look 20 years old, so the issue was most likely there from the first day.

Drain Pan

@ August 20, 2014 8:54 PM in condensate drain ?

Fortunately, we have learned to get away from pan materials that not only do not rust, but also contain antimicrobial agents to keep the nasties out of the drain line, and out of your lungs. You can clean and line the pan, yet by the time you're finished, you have a huge investment that could have gone toward a new system.

The Cooling Side

@ August 20, 2014 8:33 PM in New heating system

Is there an air handler attached to any of your existing ducts?

Keep the Boiler

@ August 19, 2014 5:10 PM in New heating system

We can help you with the AC since you have ducts in place.

Removing Boiler

@ August 16, 2014 3:55 PM in New heating system

Watch yourself here. If you go the wet coil route, the coil's pressure drop is most likely sky high. You have to account for this, and the pressure drop of your ducts and fittings, or the best system in the world won't work properly.

If you go with gas or electric heat, you still have to consider the existing distribution system and the PDs in the new unit (heat exchanger or heaters, cooling coil, filters, etc.), which sometimes gets interesting when you have existing duct work.

Renovation

@ August 16, 2014 11:08 AM in New heating system

No system "requires" humidification.

I agree with the others; why do you want to remove the boiler?

Mini-split

@ August 8, 2014 8:30 AM in problems with Mitsubishi split system

If the system is cooling yet not dehumidifying, I would make absolutely certain that the indoor coils are very, very clean. These are not easy to keep clean due to their position in the head and the rather gimpy filters the factory provides.

Humidity comes from two sources: your lifestyle and your environment. Did something change in your daily life? For example, new house plants or another moisture source. Did something change in your house? For example, an opening to the outdoors of some type.

Undersized

@ August 5, 2014 5:07 PM in Can I use a 2.5 ton coil with a 1.5 ton condenser?

We really don't know how short you are, since we only have your total load, and not a breakdown of the sensible and latent loads. Without these numbers and your weather station we can only guess. What probably will occur is adequate dehumidification on part load days due to the long run time. Yet you will have a hot house potentially; we can plot the expected performance on a simple graph for you so you will know exactly what to expect.

AC at 1.5-tons

@ August 5, 2014 10:12 AM in Can I use a 2.5 ton coil with a 1.5 ton condenser?

If you're going to use the matched coil and condenser then you have solved a lot of operational issues regarding the refrigerant circuit. However, that doesn't address the capacity of the unit and it's ability to satisfy the thermostat. Installing a unit without a load and distribution system calculation is a huge gamble.

De-rating

@ August 5, 2014 8:43 AM in Altitude and Deration

Your furnace maker has gone through a lot of time and resources to have their models listed by universally recognized agencies. Following their instructions for altering the standard operation gives you documented performance, a high margin of safety, testing agency certification, and a defensible position in court.

Oversized ID Coil

@ August 5, 2014 8:22 AM in Can I use a 2.5 ton coil with a 1.5 ton condenser?

The answer lies in the AHRI directory. If your chosen combination has been tested and is assigned a SEER and an EER value, then you know you have an approved combination.

In many cases, over sizing the evaporator will raise the efficiency of the unit, making this a good choice. However, it can bite you, too. If you do not have an approved match you can end up with humidity issues. With older equipment from the same maker that is not on the directory, call them for guidance. If the OD and ID units are different makes, don't do it, as you cannot guarantee performance.

TXV

@ August 4, 2014 5:19 PM in TXV not set properly?

Use your manufacturer's specifications for charging beyond the factory charge of 15' of tubing and the smallest AHRI matched coil.

Training

@ August 3, 2014 5:01 PM in heat pump training

Do you have specific topics in mind?

Post-leak Operation

@ August 3, 2014 1:16 PM in TXV not set properly?

You did not mention air flow. With a low TD and high superheat, that is certainly something of importance.

The Light Just Came On

@ July 30, 2014 7:26 PM in increasing length of AC cycle

Right you are; I didn't understand the question. I believe you are referring to the droop adjustment, which allows the compressor to operate to a setting lower than your comfort temperature.

If you live in an area susceptible to high humidity, three degrees is a good choice, provided you do indeed have the correct size. Dry climates should have the factory settings since you're mainly concerned about the sensible load.

Cycling

@ July 30, 2014 5:57 PM in increasing length of AC cycle

How long the thermostat takes to reach the set point is related to several things. For example, the effects of a passing weather system, the thermal integrity of the space, the size and design of the equipment and distribution system, orientation of the structure, location of the thermostat, and others. Contact your local service professional who will be happy to diagnose the reasons your system isn't happy.

Yes, we are very concerned about cycling. We want your "comfort line" to be as flat as possible, meaning on and off events are less noticeable. This helps to keep even temperatures throughout and efficiency high.

Sub Cooling

@ July 30, 2014 7:12 AM in height length line set

In residential applications, until you can obtain the manufacturer's data, you most likely are safe with 10 degrees.

AC Cycle

@ July 29, 2014 4:52 PM in increasing length of AC cycle

On the average, it takes 10-12 minutes for a properly sized air conditioner, components in good working order, to remove humidity and bring the space to the set temperature. The time between cycles depends on how quickly the space gains heat and moisture from the atmosphere. However, most thermostat makers build in a nominal 5-minute delay to protect the compressor.

George

@ July 28, 2014 8:31 PM in HVAC options for 400 square foot addition

Sounds as if this is a wonderful system, and I have no doubt the homeowner would be comfortable after your work. We are all in the comfort business and want the best end result for our clients.

However, my point is this: if you're lucky to be working with a ground-up, we have a real advantage here, and that is exactly the root of your slogan regarding conservation. We make people comfortable by replacing heat at precisely the same rate as it is lost to the atmosphere. The smaller that loss is, the heating and cooling plants need less capacity to neutralize the losses. No matter the size of the structure or design temperature; balance loss with the identical rate of comfort conditioning. It's rather simple, really. Don't lose anything so you don't have to replace anything. This logic lends itself nicely to having one unit heat and cool.
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