Is this Plumbing related?

Pop quiz. Is the damage seen in the picture above (originally posted by  ElaborateToast) caused by a plumbing related issue? The answer is below the fold so you have proper time to think on it.

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19 Apr

HVAC: Getting different answers for sizing

Link141 asks:

(Ontario) I’ve called up a few HVAC places for the installation of a whole home AC unit and getting different conflicting answers. I’m putting it in a 1645sq ft two story home, 9 ft high main floor ceilings and 8ft second floor ceilings. It faces west. There’s not a ton of windows maybe 6 on the front and in the back there’s a large glass door and large window on the main floor and 5 windows on the back of the house.

Now one HVAC company said go with a 1.5 ton and another said to go with a 2.0 ton unit. The guy who recommended the 1.5 said a 2.0 would short cycle. So which do we go with?

Answer:

A professional contractor will perform a Manual J Heat Load Calculation in your home. This will entail measuring all your walls, doors, windows, insulation, etc. He can then plug this information into a computer  program or use a “short form” to calculate what size you need. Additionally a Manual S will then determine that the selected equipment will match the load requirements for your particular climate. You can find trained contractors through local trade organizations like RSES, PHCC or ACCA. Hiring a professional who utilizes these tools may cost more upfront but will more then pay for it with long term comfort and energy efficient operation. Good luck.

James Bowman
National Technical Manager – HVACR 

11 Apr

Hot water coming out cold?

I-am-ocean asks:

In winter when I turn the hot water on in faucet cold water comes out eventually getting warmer to hot after about (x) seconds, Why does this happen and how do you fix it?

Answer: I would like to recommend a product http://aquamotionhvac.com/hot-recirculation-systems/ as a simple solution. Meaning does not require running a new return pipe across the house. Install it under the sink at your farthest point from the water heater (which faucet takes the longest to warm up. it is very economical to operate but you have to decide which cost you more, electricity or water. This one operates at a cost similar to a 40 watt light bulb. I installed this pump a couple of months ago and have very pleased with the results. A non-professional can install it depending on your level of comfort and handiness. Please hire a professional if you do not fully understand any of the process involved. A water leak or electrical issue will far out way the cost of a professional. Hope this helps – James Bowman, National Technical Manager, HVACR

30 Mar

THE HARD START & POTENTIAL RELAY

I have spent most of my career being afraid of hard start kits, I heard too many horror stories of start caps exploding and sales technicians telling every customer they need one.

It dawned on me recently that it may be time for me to take a more mature look at start capacitors, potential relays and hard start kits and find some best practices.

Let’s start with how they work.

When a compressor first starts up, it requires a lot of torque to get from 0% up to 75% of running speed, especially when it has to start under pressure load (unequalized pressures). A start capacitor is designed to create the optimal phase shift for that first 75% of synchronous speed. A run capacitor is sized to create an optimal phase shift for a compressor that is running at full speed and at full design load because the run capacitor never comes out of the circuit.

While a run capacitor has heat dissipation capability for constant duty a start capacitor MUST be taken out of the circuit VERY quickly to avoid melting down as well as causing compressor damage.

The start capacitor is REMOVED from the circuit by a relay called the potential relay. The potential relay is normally closed and it OPENS when a sufficient PICKUP voltage is present between the 5 and 2 terminals on the relay. This pickup voltage is potential (voltage) that exists in the start winding when a motor gets above about 75% running speed and it is GENERATED in the start winding by the motor itself NOT the capacitor. A capacitor DOES NOT boost the voltage, when you see that increased voltage across the capacitor that is back EMF being generated by the motor, just like in a generator (pretty cool huh?).

Some hard start manufactures wire the coil on the potential between start and common and some wire it between start and run. You will find that most OEM’s wire between start and common but this does not mean that wiring between start and run is bad… it just needs to be designed correctly for that purpose (Kickstart does it this way for example).

A properly sized start capacitor and potential relay are not BAD for a compressor, they just must be sized and installed correctly and there are some cases where they are more likely to be useful that others.

Cases where they may be very useful useful

  • Long line set applications
  • Hard shut off valves
  • More often on reciprocating compressors than scroll or rotary (but still OK on scroll and rotary when beneficial)
  • on 208V single phase applications

Things to consider

  • Mount the relay properly, there is a proper UP configuration on most potential relays
  • Use hard starts with REAL potential relays not timers, solid state or other relay types (in my experience)
  • Size the relay and capacitor according to manufacturers specs
  • Ensure that you have a good quality, properly sized run capacitor on any system with a hard start

For a complete write up on potential relays you can read these articles HERE and HERE

source: hvacrschool.com

17 Mar