TXV and temperatures

The typical TXV comes factory set for 8-12 degrees of evaporator superheat, which in most cases should be fine. What is the correct setting for evaporator superheat? While it is true lower superheat will make the evaporator more efficient, we need to be more concerned with the compressor or total superheat. If we check the superheat on the suction line 6” from the compressor we should normally have at least 20 degrees of total superheat. This will ensure the compressor is not slugging with liquid even when frost is present. The suction line temperature at the compressor should not exceed 65 degrees to ensure proper compressor cooling. The last but most important reading is the discharge line temperature taken 6” from the compressor. This temperature should never exceed 220 degrees, as higher discharge temperatures will lead to compressor failures. Reducing superheat will lower both the compressor suction line and discharge line temperatures.

Comments

Post a Comment

Popular posts from this blog

Heat Pump Refrigerant Flow Chart

Image
Heat pump system basically works in both winter and summer time because it converts condenser and evaporator role. In winter time, the indoor unit becomes condenser and outdoor unit becomes evaporator, in summer time, the indoor unit becomes evaporator and outdoor unit becomes condenser. The liquid line out of the compressor always contains liquid, the vapor line into the compressor always contains vapor. When liquid hit reversing valve, things change in winter and summer mode. See the chart below: The refrigerant lines that connect the indoor coil with the outdoor coil are the gas line (hot gas in winter and cold gas in summer) and liquid line. The liquid line is always the liquid line; the flow reverses from season to season.
Read more

租房 - 别人的经验之谈

不合格的房客我们不安排看房， 不想要的房客被我们过滤掉 了。 剩下的少数也就是我们的“准房客了”。 一般情况下，我只接受这些人的申请， 给这些人提供申请表格。 下面是我一般流程，分享给大家。 第一步： 申请表，工资单，驾照照片。缺一不可。 申请表最重要，里面的信息是核对房客信息的基础。 申请表一定要有签名。 大多数美国人不会写字，有时候数字难以辨认。 别的信息驾照上面有， 社安号码一定要再确认一次。 驾照一定要照片，最好是彩色的，这样房客不容易作假。 我曾经遇到过一个有意思的租房申请人。一个40岁左右的男人，穿着体面，谈吐优雅。他说自己是一个公司的高层，家在三藩市，在南加州上班，所以想在南加州租个Condo，平时住一下，周末一般回三藩市和家人团聚。 他有一点东北口音， 自称是台湾人。我收到他的申请表，向他索取驾照。要了两次，他勉强给了我一个黑白复印件。 那个复印件上的信息一看就是假的，字体都不统一。 我回想一下，觉着这个申请人非常可疑。他来过三次，看房一次， 交申请表一次，给驾照复印件一次。 每次都是晚上9点左右来到，开一个小破车。 和他的西装革履一点也不相称。 我直接把他拒绝了，打电话说我一定要看到他的驾照原件才能接受他的申请。 他说没有问题，就再也没有出现过。 我到现在也想不明白他是怎么回事。 工资单也非常重要。我一般需要房客的收入是房租的3倍。 但也不是3倍就一定可以。 工资单可以看到申请人有没有Wage Garnishment。 例如一个申请人月薪7千， 抚养费可能需要2千。那他的可支配收入就是3500一个月（税后）。 只能负担得起月租1300左右的出租房子。 如果我遇到自雇的申请人，我会要求看申请人去年的个人税表。 个人收入一定要合理。 我遇到过一个华人家庭，女主人开着奔驰来的, 看起来就是不差钱的家庭。 两个孩子也有礼貌，有教养。 他们的爸爸在亚洲上班，在美国报的税是低收入水平。 他们的申请表上收入很少，银行账单只有几千的存款。  我没有接受了他们的申请。女主人很不高兴，说他们家在香港有许多存款，钱没有放在美国是因为怕孩子们读大学的时候失去低收入的补助。 我说对不起，我只能看你能证明的收入。我当时的私心是怕他们做饭的油烟太大，我的那个出租房没有烟道可以排烟到外面。 申请表上如果有被驱赶过的， 有破产过的我绝对不考虑。他们都经历过各种法
Read more

AC capacitor test

Image
 if the capacitor marked 45/5 for example, then the Fan to common should be tested around 5 mfd, then the Herm to common should be tested around 45 mfd, there should be also +- like 6%, that will give a range. If they are out of the range, then the capacitor should be replaced. Also if capacitor is bad, when you manually push the contact, the condenser will try to start with some sound, but eventually it cannot, with this test, you can pretty much confirm that the system most likely need have capacitor replaced. in terms of the wiring, herm goes to condenser, fan goes to fan, common goes to L2. in terms of the color code, fan wire should be brown, common should be blue, herm should be yellow, but sometimes the color get messed up, you will have to make sure the wire (whatever the color might be) are connected to the right terminal. So to make it even more clear is that the herm terminal on capacitor should be connected to the compressor S(tart) terminal. C(ommon) on capacitor should be
Read more