Instruction: Given a question and its related document, determine if the question is answerable by analyzing the information in the document. Output yes if the document addresses the question, or no otherwise.

Input:
Question: I just installed this valve. Water flow when we turn on the faucet is very low, almost unusable.  Is there a rated water flow for normal use??
Document: We paid to have a hot water circulator 'retro fitted' in our 10 year old home. They put one comfort valve in the kitchen. It did not work at all. Then I read the small manual on how to check if the comfort valve is working (turn off the cold water under the sink, open the cold water faucet, should have flow that slowly drops to a trickle). We had a bad comfort valve. Plumber left a new on my porch, I installed and the system worked great. I have 'branch' hot water piping, so I have to put these comfort valves in the kitchen and both baths.
I bought only this piece after reading an earlier review that this can work by itself without the recirculator. The post basically said that this would work since there's a thermometer in the piece that would allow the water to flow naturally without a motor (recirculator) performing the work. This is not true! I've installed the unit at the farthest faucet from the water heater and nothing. The water remains as cold as without the piece. I've decided to leave it installed since I would not want a $50 piece laying around doing nothing, but collecting dust.
I wanted to try this product so the hot water line is always hot. In basic Physics, we know water can not flow between two lines unless there is a pressure difference. I just install this valve between the hot and cold water lines. It didn't not work. My hot line is at the ambient temperature. I gave a three-star natural rating because I can't use this valve. This souvenir valve is the reminder of the basics of the physics.
My second Comfort Valve died about a year ago. I'd been living with the additional hot water in my cold water pipes until I said &#34;Enough.&#34;  This unit directly and easily replaced the earlier unit. It seems to constrict the hot water flow a little more than the other unit did when new. Nevertheless, it works.We have soft water but that didn't stop the old one from clogging. I cleaned it out and hope to use it when this one inevitably clogs after one or two years.
If you are not using a Grundfos recirculating system in your home, or selling them to your customers, you are pouring thousands of gallons of cold water down the drain, waiting for the water to get hot at the sink or faucet. This inexpensive valve is the jewel in the crown of home use; as a landlord, this makes your tenants really happy; as a plumber, you can save your customers time and money on their water bills and water heating costs. I find that in "hard water" areas (or not filtered supply lines) the valve at the furthest faucet becomes ineffectual after 4 to 5 years.
I just installed a recirculating line in my house when replacing the pipes. Unfortunatly, I have one sink (kitchen) that isn't on the same "line" as the rest of the house, and didn't want to spend the $$ for labor or pipe to run an additional  line all the way to the one sink. This thing is perfect. I don't have a pump, my water heater is in the basement, so everything is driven by themal convection. Not only do we have hot water in the kitchen when we want, we also don't have to worry about pipes freezing (exterior wall...Chicago) because the valve opens to let hot water flow.
I recently installed the Grundfos Comfort Series hot water recirculation pump. I installed the comfort valve that came with the unit in the master bathroom, where I saw an immediate reduction in the amount of time it takes to get hot water from the water heater to our shower.I Purchased this second comfort valve and installed it at our kitchen faucet, we now have instant hot water in our bathroom and kitchen.
We've had a Grundfos hot water recirc pump for almost 10 years. We recently noticed hot water coming from the cold side of the sink where the valve is located so I suspected the valve may have failed. We live in the metro Phoenix, AZ area and have very hard water and after doing some research I thought the valve might have finally succumbed to the hard water. Amazon was the first place I looked for the valve and was a little surprised (and pleased) to find it available. I ordered it, it arrived quickly and my plumber installed it and now everything works great again.
Better than letting the faucet drip. The only negative is, since it uses the cold water line for a return, you'll need to let the cold water run to flush the warm water out of the pipe. I use warm/hot water in the kitchen MUCH more frequently than cold, so this isn't a problem for me (and it doesn't take long to get COLD water in Chicago :O)
This valve is a part of the necessary functioning of the Grundfos Pump listed above, (installed on the water heater) to speed the readiness of hot water at each faucet you want or need. You will need one of these for each faucet at which you would like to have instant hot water.
Answer: yes