Plumbers - pressure compensating flow regulator
 

Anyone ever install one of these babies? Got any advice for manufacturer?

My goal (maybe can achieved some other way) is to get a constant flow rate to my shower. I have a well and pressure tank, and my pump is set to turn on at ~35psi and off at ~50psi. I have recently installed an on demand water heater, and it does not have thermostatic control. So the water temperature is raised x degrees at x gpm. When the pressure runs down to ~35 (less gpm), the water is hotter, and when the pump kicks in to boost the pressure back up (more gpm), the temperature dips. It's not a terrible difference, but I like a consistent temperature. Possibly I could use a pressure regulator and set it at the lower end of my range?

The crux of the problem.

The old gas fired tank.........cheap........reasonably efficient..........and a steady supply of hot water.

No gas in this house (except for the unregulated kind)
The on demand water heater has almost paid for itself in three months.
And, I needed the space. The on demand is the size of a briefcase.

I'd love to see an honest comparison of this.

Was the previous system an electric powered storage tank?

Two things you might try on the cheap; boost your low pressure to 40 then install the regulator, on the shower hot water supply only.

A better solution in all respects is to increase the size of your pressure tank. The root of your problem involves "drawdown"; your tank is too small. Most folks have a nominal 20 gallon tank at best when they should have a 60 or even 80 gallon captive air tank. If you had a 100 gallon you wouldn't know that you were on a well, it is as though you have municipal water; ask me how I know:D

Jim

Yes it was, and it was not the most efficient either. My only comparative data is my electric bill. Saw the bill drop from $475 to $300. Staying pretty consistent at that rate. Of course, during this time, my wife was pregnant, and taking baths every day. And the two kids still take baths as well. (no, despite my asking, they still tend to take separate baths) Then there's the laundry as well. Bottom line is we use a butt-load of hot water.

EDIT - I just reviewed my electric bill over the past year, and the savings of the demand water heater seem to be more on the order of ~$60/month

Jim, I like the sound of that. I do have a small pressure tank, sealed also. The larger tank would also allow the water from the well to heat ambiently in the basement, increasing the final output temperature.

The other upside of a larger captive air tank is that your pump will cycle less often, greatly increasing its useful life and saving you another hunk of change on your light bill. The electricity draw at startup (most pumps are capacitor assisted at startup) is substantial compared to sustained operation. The fewer times it starts, and/or the longer the run time per start, the more efficient.

We usually recommend a tempering tank (can be a simple inexpensive steel tank) for tankless heater installations, especially if you can locate it in a warm location, like a mechanical room. But you are correct in that a large pressure tank would serve that purpose as well.

All that said, the big tanks are quite pricey; however, I would say without hesitation, a good long term investment.

Jim

Don't suppose you could tie two together? My current tank has no way to adjust the pressure, is that a normal thing to find? I recall the one we had growing up had a valve stem. What are your experiences with water softeners? I adopted an old 50 gallon Master. Can't remember the model number, but it uses salt.
Thanks

Oh yeah, how do you know?:D

Yeah, I had a little 110vac electric tank in series with my instant hot water heater. Used a little bit of electric, but it meant I had hot water quicker and it smoothed out the temperature fluctuations. My experience was the tankless saved a dollar a day at about 8 cents per KWH.

What is maintaining the pressure in the tank is the air that is trapped in it, not the amount of water it holds. A "captive air" tank has a rubber/neoprene "bladder" built in. It serves as a tank within a tank to separate the air and water, this ensures that the air does not escape. The air is what stabilizes and maintains the pressure. Without the air cushion the pump will come on every time you open a tap.

Except for the smallest, least expensive models, captive air tanks normally have a valve to set the air pressure to balance. The plain jane steel tank you had growing up was fed a small charge of air with a diaphram setup on the pressure switch each time the pump started (do you also remember the small copper tube between the tank and pressure switch?). The valve was there to manually "recharge" the air in the tank if it became necessary. If you don't mind the hassle, you could probably get by with installing a large inexpensive steel tank, plumb in an air valve, and once a month or so, drain the water down about halfway and use a small compressor to recharge the air.

I installed a 100 gallon captive air tank about 15 years ago and wish I had done it 20 years sooner. Pressure swings are not at all noticeable and it takes a half dozen toilet flushes or a complete shower, before the pump kicks on.

Jim

Like the others said, get your pressure fluctuations under control first with a proper tank. Then, if you still have problems, you can use a tempering valve to accurately regulate the temperature in the hot water system.

Here's an example:

http://cgi.ebay.com/TACO-3-4-Sweat-Mixing-Valve-5003-C2-Tempering-Valve_W0QQitemZ230325501272QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item230325501272&_trksid=p3286 .c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

As for water softners, a modern demand based unit will have much better performance than the older one. You can go to Lowes or HD and pick up a test kit to test the hardness of the raw water coming out of the ground. Add this to the anticipated GPM water use and you can find the appropriate system. As far as I know, all softners use salt brine to strip the ions out of the resin core. A few years ago, I put together a green sand filter and a water softner from CSI to deal with sediment in the well water. Both systems are self-managing except for adding salt and neutralizer.

12.5 Kwh per day
375 Kwh per month.

750 Kwh per two months.


Just to make a point:

My entire electric bill for a two month period is 750 Kwh on a four bedroom colonial with typical appliances and a gas stove. The usage rises to 900 Kwh in the summer months when the window a/c is in use.

I think your experience must be significantly in error. There is no possibility of saving this amount of energy unless you're using thousands of gallons of hot water and your electric bill was 2000 Kwh per month prior to the installation of the tankless heater.

I installed a pressure regulator recently in a client's house. It was on the water line feeding the older style radiator heater. I had moved the separate water heater for that (?!? - I didn't design the system) in order to facilitate the sewer clean out in the basement and noticed that the existing valve seemed to be inoperable.

The pressure up in the Berkeley hills is pretty strong for some reason (close to a gynormous tank up the hill, perhaps) and I gather too much pressure is not good for the radiator and of no use at any rate.

I forget the brand, it was a bell shaped thingy about 4 or 5 inches tall. Just goes in the middle of the line. About $50 - $60 bucks IIRC. Not sure how steady the delivered pressure is. Probably has an off and an on pressure but likely to be much more sensitive than what you have now.

Prior to tankless installation we were averaging 50kWh per day, at ~20 cents per kWh. High point was 76 kWh per day in January, for a total usage of 2356 kWh for the month. Since the installation, we're down to about 30kWh per day. So we're down about $120 month. Of course we have been making other conservation attempts as well (read - Daddy turns the lights out wherever no one is using them). I would put the savings of the demand water heater at ~$60 per month (absolutely no basis for that number), and the rest being other efforts. Not nearly as big as I has originally posted, but still a fair amount.

Wish I had a two month usage of 750kWh, *****, I wish I had a 1 month usage of 750. I think I need to get my own meter.