Washington Hp Home DIY Geothermal

After several months of focusing on other projects I am back to working on the geothermal system.

I have not been able to do a wiring drawing because I am having problems with my cad program.

For the most part it is simple enough but I am not fully understanding the reversing valve/ 3-way valve wiring.

The HBX eco550 has 2 terminals (5 & 6) for the heat pump, and 2 terminals (18 & 19) for the reversing valve.

The heat pump has 3 terminals- Y1 compressor, R 24V and O/W2 cooling.

The Belimo 3-way valve actuators I have both have end switches. They have terminals 1, 2, 3 for the valve and S1, S2, S3 for the end switch.

If anyone can help me understand this I would appreciate it very much.

 

This should be a good start and is submitted for discussion.
Some assumptions are made based on my previous post here (I have not included end switch wiring at this time)-
https://www.geoexchange.org/forum/threads/hp-home-diy-geothermal.6647/page-9#post-59399

 

Thank you Geoxne that is a huge help!

Where do I connect terminals 5 & 6 on the eco-550? Originally I was thinking they went to R & Y1 on the heat pump.

Also I had been thinking that terminals 14 & 15 on the eco-550 would be used to turn on the load pump. Would that be turned on by a 3-way valve end switch?

 

I discussed running your HP as "HP 2" at the HBX with a one minute lag time with no rotation to allow time for valve rotation. So no connection to 5 & 6 in that scenario.

There is no need for the HBX to control the HP load pump to the buffer tanks. Your HP will do that nicely. Simply wire a 230v pump to the same terminals as the ground loop pump.

Let me know if I'm heading in the wrong direction.

 

Thank you this is the right direction.

I didn't realize I could power both pumps off the heat pump.

Source pump I did that way but for the load pump I already have a 115V pump and a relay.

 

The HP Load pump only needs run when the compressor is running. If your relay has a 24vac input coil your can activate it with the "A" terminal on the Climatemaster CXM board. The "A" terminal 24vac output is energized only when the compressor is called to run by the CXM board.

 

I assume with using "A" to switch the load pump relay that I can use "R" at the heat pump or junction box for 24V?

Are end switches on the 3-way valve actuators not even needed?

 

A word of advice for anyone shopping for heat pumps- avoid models that use the POE oil! Had I known about this in advance I might have gone with a different brand. Copper pipe versus cpvc is a huge difference in both material and labor cost and should be taken into account when pricing heat pumps.

That being said copper is nice stuff and looks good too. Here is a progress pic of my cluster of pipes-

 

Nope. You'd better sell that house before you have to replace a tank.

 

I know it's not going to be easy to work on but how often do you replace tanks?

A different layout would have made the tanks more accessible but all the piping and components less accessible.

Volkswagen makes cars that are easy to work on, Toyota makes cars you don't have to work on. Hopefully I am building a Toyota here.

 

Yes. I'm not trying to be harsh. You can realistically expect to replace something within 10 years. Less if you have poor water quality.

Generally, nothing goes behind anything else. I'd have it up on the wall behind.

 

Just confirm what is in the picture. What does each tank do? Why 2 tanks?

 

Those are hot and cold buffer tanks, hot is on the right. The mess of copper in the foreground is 3-way valves, load pump, air and dirt seperators, etc.

I wanted 2 tanks so that in spring and fall I can keep the downstairs slab heated for cool mornings but have ac upstairs for warm afternoons.

 

Thanks I appreciate the feedback as this is all a learning experience for me.

My original plan was to have it all up on the wall behind but then I would have been climbing over the tanks to put it all together. Cpvc would have made that easier but with copper I had to be able to solder. I was also figuring a component like a circulator would be serviced more often than a tank. I hope the tanks last a while they were not cheap.

 

OK, now I recall your desire for both heating and cooling at the same time.

 

I am planning to use methanol for antifreeze in the ground loops but I am not sure exactly how much I need.

I have 2400 ft of 3/4" sdr11 that I am estimating to hold about 70 gallons.

Plus a flow center, about 12' of 1.25" pipe and the heat pump.

Is 80-90 gallons a reasonable estimation or should there be more (illusion of) precision?

I was thinking 20 gallons of methanol should be sufficient. Right now the loop field runs at 53*F but I'm not sure how fast or how much that will drop once I start using it.

 

You seem to be on target. I would put 22 gallons in, methanol freezes pretty quickly

 

The btu's have started moving and this is now officially a testimonial thread

 

I still need to figure out how to turn on the load pump. The heat pump has a terminal "A" on the P2 terminal strip but I am not sure what to do with the other wire.

Also I still need to tinker with the auto changeover. When I started the system in heating mode the load out valve kept going to cooling mode. I manually set it to heating and disconnected the wires so it would stay.

Later I realized the hot/cold tank thermistors were reversed so I fixed that but I'm not sure if that is what was causing the 3-way valve to misbehave.

The load in valve had no problem staying in heating mode. I have not yet ran the system in cooling mode to really test the changeover.

 

You mentioned you have a relay for the 120v load pump. The "A" terminal will energize a 24v relay coil. The "other wire" from the coil would go to the "C" (common) terminal to complete the circuit. Let me know what you have for a relay and I will look it up to confirm.

The actuator head on the "misbehaving" may have to be rotated 90 degrees in relationship to the valve. Also, the direction of travel can be changed from CW to CCW with the slotted arrow on the actuator.