While I'd gone as far as I could with the copper piping installation and I have a day to identify and compile the next online order by Sunday night. As everything is a week away my goal is to able to complete the plumbing and have all the critical material on hand by the end of the month.
One critical task is to test out the diaphragm pump's pressure adjustable range. The pressure I want from these generic RV/marine pumps are contrary to what the typical buyers want. They want pressure like household water supply of no less than 45 PSI, while I want it between 15 and 25 PSI. I have reservation that the pump's pressure switch adjustment could be set that low.
my essential copper soldering tools
This is a very nice pump for the money. It is quiet and moves plenty of water. I was a bit concern with the barb fitting they intend you to use as it looks on the weak side to be used with a PEX tubing. I tried to not use the barb fitting on the outlet side, but only to find the thread and diameter is metric.
looks like 1/2" MIP
but is parallel thread 22mm metric
except it needs an o-ring at where it mates with the plastic port; I managed to find one in my collection
I chose this pump as it comes with garden hose brass adapter
The garden hose adapter came in handy for the bench test that I were to perform next. The pressure test. Were I into some big surprise. I had no experience with these very common pumps used in typical US RVs (except they are typically 12Vdc).
my simple bench test setup
The garden hose brass fitting allowed me to use a common household water pressure gauge.
the pump would turn on at around 45 psi and switch off at 55 as shipped
by adjusting the pressure switch set screw all the way CCW I could barely lower it to 38/46
so I opened the pressure switch compartment to investigate but there is nothing I could do inside
I also thought may be I can simulate a cushion with a garden hose to soften the blow
In the end I realized the other element that determine the pump's on/off hysteresis is the internal mechanical bypass. It manages maximum pressure impulses of each pump stroke. Unless I can adjust that too there is no hope of achieve my target of 15 - 25 PSI operating range. Attempting that is a fool's errant.
I was hoping I could get away without investing in a feed pressure regulator. Once I realized how these pumps work it is crystal clear that the hydronic pressure regulator is a must for my system, and this pump is perfect for my design.
I scrounge through my hose collection to look for a hose more flexible so not to put undue stress on the pump's plastic nipple. I found this thin wall polypipe with the oversized 3/4" MIP fitting that I made for a previous test project. I need a 1/2" MIP.
this would work if only this poly pipe has a 1/2" instead of a 3/4" MIP fitting
I look more and found this short one with a 90 MIP elbow. If I just transfer the 1/2" fitting over to the longer hose it would be perfect for what I need. The 90 degree elbow will allow me to mount the pump in the best orientation with the ports opposite to my layout by reversing the supply and outlet orientations.
it even surprised me what I constantly find in my collection
Once I determined exactly the parts I would need for the system feeder and mounting the expansion tank I could accurately compile the shopping list.
I chose a thermostat with additional slab sensor. It looks 95% identical to the Tekmar I bought 18 years ago. It is now Honeywell. The styling of the current Tekmar offering are totally different and ugly. Tekmar must had sold the whole design portfolio to Honeywell.
this bears the hallmark of the old Tekmar design, though the old was was in fact cleaner
the current Tekmar styling is unacceptable
I will buy none of these
Out of all the hydronic thermostat offering out there it was very easy for me to choose that one as most styling offend my sense of esthetics. When I travelled to Korea and Japan most hotel room has a cleanly styled thermostat that is always rectangle. There is no reason to embellish them by putting ugly curves as most in the US have done.
this is one in a hotel in Shinjuku, Japan
this is for the central air/heat pump for the main house and it assaults my senses
I didn't want to spend the money for a new thermostat by using my old Honeywell for forced air HVAC. The one like Tekmar that has a slab sensor is necessary for my intended use of the hydronic heat as a supplement to the mini split. It could be programmed for freezing protection better than the LG mini split.
I added the thermostat to the shopping list.
Now is time to sit back and relax until the parts arrive in a week, almost. I realize procuring circa 20 gallons of concentrate glycol may take some time as a gallon weighs about 8 pounds.
I think I will order 20 gallons to be on the safe side
The hydronic industry is very happy to sell you overpriced glycol at 4x of those made for automotive. I am not stupid to fall for their FUD marketing. I buy the cheapest house brand coolant in concentrate. I tried to order online from Walmart but they will only let me order up to 12 containers at a time. Idiot! 😠 I had to do 2 orders to get what I need. I am very curious how Walmart is going to ship 12 containers of my first order. 🍿Their online order system is designed by idiots. You cannot type in "12". Instead you click the quantity increment or decrement arrow, and each time wait for the page to refresh.
the cheapest glycol money can buy
specially formulated 🙄 glycol for hydronic costs $60 a gallon!
Hydronic floor heat in the US is promoted like the Lamborghini of home heating because everything is overpriced, especially finding a competent installer will cost you. Their popularity in the US has been greatly increased in recent decade due to DIYers take it upon themselves.
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