I need some suggestion for troubleshooting for the load side of a synergy3d. The hydronic side is putting out 128F, incoming is about 100F. Delta for the loop is 6, flow about 20 gallon/minute for a 6 ton pump (loopside). Piping to the buffer tank is 1.5 inch copper, the tank is isolated from the floor heat so far with ball valves. Air is purged out of the loop and the load side. Any idea why I am getting such a high temp delta on the load side? no restrictions in the load loop between the pump and the buffer tank Thanks

You don't tell us how long the system has been running. If after several days of more or less continuous operation it doesn't come down then start to look for problems, after the loop(s) have begun to modulate.

I can't conceive of any explanation other than low flow on load side. Doing the math for 6 nominal tons of heating as a basis for discussion yields a load side flow of 5.1 GPM.

I can't imagine how waiting several days will change matters much, other than a drop in loop side EWT reducing capacity by 10% or so.

What is the design flow for the load side? Has the installed pump's curve been evaluated against the actual plumbing (lengths, fittings, etc)

Start with the basics.

the system runs for about a day now. The problem is that with a 28 F delta I have a 110 incoming into the pump and a 135 leaving. I cannot get my storage tank above 110 , which is not enough for the house. Spec sheet says load delta should be between 8-15F

That you can't get enough heat into the tank further supports low flow. The higher LWT is reducing the unit's capacity by a fair bit, I'd guess 10-20%. It is also reducing efficiency and is hard on compressor and other refrigeration side components since it subjects them to very high pressures

I hear you, I agree that there it is likely a flow issue, but I am scratching my head, since i am going only in and out of a storage tank with 1.5 inch copper lines. The only thing are 2 ball valves (obviously both open). I simply have no idea where the flow restriction might come from. Anyone else had this problem?

docjenser

What are you using for the loadside pump to the buffer tank? An incorrectly sized circ pump will effect flow.

Also what are you using for your buffer tank? What are the inlet and outlet sizes?

Maybe clarify a few things here.

The original post states that the hydronic floor loops are 'isolated' at the moment. Does this mean the floor loops are shut down?

A synergy3d HP combines the air handler for forced air heating with a separate circuit for feeding to a hydronic load via a storage tank. IF the floor loop(s) are inoperative the circulation pump, HP-to-Storage  may not be running as the tank portion of the system is not being used.

If the floor loop IS operating then suspect a flow problem in the HP-to-S loop that supplies the heat to the tank.

All of the above is based on interpreting the problem description.

The synergy3d literature is not specific as to internal temperature levels between the two portions of the unit so it is hard to interpret exactly where your measurements are being taken too.

Delta T should be under 15F on the load side of the 3D. If there is no restriction and no air issues you have a pump problem (assuming it is plumbed correctly). The internal pump on that unit is a UP26-99. I strongly suggest you double check the plumbing connections at the unit and refer to the install manual for proper connections. The top and bottom connections (of 4) are load out and in.

Yep, it is a 26-99, leaving out on the bottom connection, coming in at the top (above the 2 connection for the outside loop). Still getting 26 F for a delta. Will put in a new 26-99, alternatively, has anyone had a plugged up heat exchanger?

Groundfos 26-99, standard for the synergy3D. buffer tank is 75 gallon (120 geostorage tank is ordered), inlet and outlet are 1 inch, piping tank-HP and back is 1.5 inch copper.

The floor loops are not shut down, I just isolated them with 2 ball valves just to better deal with the problem. I am getting flow to the storage tank, but I get a 28 F delta, thus the tank gets only to about 105F before I reach 133F in the LWT load side. Too much stress on the HP....need to get the delta down. PS: was getting 10F delta for the first 15 minutes while heating up the storage tank, then opened up the floorloops, then getting 28 F delta, shut down the floor loops again, 28F delta remains.... I am down to put in a new 26-99, or the heat exchanger is plugged. Air is out. Any other thoughts?

Is this a conventional electric water heater? If so, what fittings are you using for inlet/outlet and did you remove the dip tube?

The fact that you had a lower dT at one point strongly suggests a slug of air or debris blocking something. Can you measure pressure drop across the pump and/or heat exchanger? Then you could estimate your flow rate. Though a 28F dT is so high that either the flow is low or the temp peasurement is off. Where and how are you measuring the temperature?

temp is measured on the pipes halfway between the HP and the tank. There are about 15 feet of pipes with 5 elbows each way. I don't have P/T ports in on the load side, will 1) flush the system again, 2) burp the pump again, 3) exchange the 26-99 pump 4) Report back

This is a 8 year old tank (non-electric) with cold in and out on the top (which i use for floor loop in and out), and 2 more ports, one on the bottom, one at the top, which I use for in and out from the heatpump. Should be straight forward, but it is not......

Load side P/T ports ARE required. Without them you are just guessing.

Bergy

Before you swap a pump out pull the motor and impeller out and look for anything blocking flow. Take a close look at impeller blades for scraping marks or distortion and check the housing for same. Solder balls and pipe reamings are the most common culprit.

Problem still the same. P/T ports going in tomorrow. I usually only put them in only on the source side, never had this problem. I will then also pull the pump motor and check the impeller. I keep you posted...

OK...problem solved. After putting in P/T ports, there was almost not pressure differential between in and out. I removed the pump (could not get to the motor without removing it, and calcified debris had plugged up the impeller. It came from the older storage tank. I was asked by the homeowner to keep it so he could save some bucks for the storage tank. It looked and worked fine so far. The whole thing taught me 2 lessons: Never take older equipment into the system since you are the one paying the price for it. Always put p/t ports also on the load side, since it would have been a few minutes to locate the problem. Thanks everyone for the help and input.