New HW Heater, flow drops! Please Help!

So I had a new hot water heater professionally installed. Local plumber who contracts with Lowe's for their installations. Now when I turn on the hot water in one location the hot water flow at the other location drops. The plumber who installed has been unable to determine the cause. There is NO drop with cold water only the hot. He feels it is something to do with the HW heater but says it checks out fine. Does anyone have any thoughts or ideas? He tested the thermal expansion tank and said the pressure there is fine. Please help...this really is no fun when I'm in the shower and my wife runs the kitchen sink!


Thanks!

Do you know what tests he has done to the new water heater to determine that it is not the problem?

The shutoff valve does not appear to have been replaced, has he checked it?

Can you shut the water off to your inlet to your wh. Then unscrew your flex coper line on the hot side and direct it into a five gallon pale. Then turn on the cold valve. What kind of flow do you get. That should at least help you eliminating the problem being your heater.

It looks like you have a read & white gate valve on the supply line of the heater. They have been none to break in the closed position. Try turning it counter clockwise. If it just continues to turn with out stopping it's broken.

Thanks for the replies!
Yes, cold water supply was checked, it is fine.
Plumber does feel like there is somehow lack of flow from hot water heater.
He said he was pretty sure the "red and white gate valve" or shutoff valve was okay as it opens and closes easily although he did offer to replace it for $140 but wasn't sure that was the problem. He did say there are some plastic "valves" at the outlet of the heater itself which can sometimes become defective or blocked. He said those were fine. So does it sound like a good idea to try to replace that valve? Any other ideas?

Thanks!

spete112 said:

Can you shut the water off to your inlet to your wh. Then unscrew your flex coper line on the hot side and direct it into a five gallon pale. Then turn on the cold valve. What kind of flow do you get. That should at least help you eliminating the problem being your heater.

Click to expand...

^^
I would start with what he said.

phishfood said:

^^
I would start with what he said.

Click to expand...

Follow up: The water connections to the hot water were overtightened and the plastic valves seemed to be splayed out. . They were removed (another plumber said they were not needed) and then everything was back to normal.

I think some newer water heater have a valve built into them to prevent thermo- siphoning, wasting heat.

johnjh2o said:

It looks like you have a read & white gate valve on the supply line of the heater. They have been none to break in the closed position. Try turning it counter clockwise. If it just continues to turn with out stopping it's broken.

Click to expand...

I agree with this ^^^^

Gate valves suck

A quick check to narrow down the source of the obstruction would be to attach a hose to the heater flush and drain valve. Then check to see what kind of flow you get there into a floor drain or bucket with the cold water inlet valve open.

I presume you have solved this problem by now as your original post was from November 27. But, in any case I had a couple of additional thoughts.
1. If your inlet gate valve is like mine, it has a hex on the bonnet which would indicate it could be unscrewed to inspect the condition of the valve. If the gate is off it is probably not repairable, but you at least will know it is the problem.
2. If you disconnect the cold water inlet to the heater, you should be able to inspect the check valve that is likely there to see if there is something in it. Not sure it is possible, but the other possibility is that the check valve is in backwards.

Did they put any strapping on that expansion tank. It will get water logged at some point and become very heavy. It looks like it is just hanging from the threads

as someone else stated, water heaters have limiters on the outlet valve to keep heat waste at a minimum. The last two water heaters we have bought limit the flow of hot water, even if that is replaced with a straight nipple. The washer, which sits right next to the hot water heater only gets about 1/2 the flow of hot water as cold water. This appears to be by design to keep heat waste to a minimum. The shower, sinks etc., are so limited on how many gallons per minute they can flow one will not sense it. However put a heavy demand for hot water and the GPM is limited, thus reducing water pressure in other parts of the house.

Thermo heat traps are the plastic crap from the nipples in the water heaters...

Anyone put a pressure gauge on the inlet and outlet of the water heater?

PRV and expansion tank are set to 60 psi. For most fixtures the drop in minimal. Hot water on full at the washer is 52 PSI at inlet. Cold water on full at washer is 50 PSI inlet. With warm on, eg., cold and hot flowing, the inlet drops to about 43 - 45 PSI, which is a 15 - 17 PSI PRV fall off. Cold volume at the washer is always much more than hot. I have rebuilt the PRV several times because we get a hammer when the sprinklers come on. This never happened before the expansion tank was added but now does it even if the expansion tank is turned off. I have added water hammer arresters at the sprinkler line inlets but that accomplished nothing. Plumbers have not a clue on dealing with either the balance issue or sprinklers hammering when they come on.