Unlimited hot water

[PineRidge]

Are you refering to those systems where you put a 'bypass' at the faucets and run a recirc pump so you always have hot water at the facets?

See this


My system uses a dedicated return from the furthest faucet and a pump to keep hot water circulating at specific times of the day.

 

[schweizer]

Ooops, I was wrong. We have a Rheem water heater. Model #: RTG-84DVP

 

[Allee]

I try to locate my owners manual. Thanks

 

[aczlan]

I try to locate my owners manual. Thanks

The link I posted earlier ( http://www.houseneeds.com/shop/manuals/bosch_250sxmanual.pdf ) has the owners manual for your unit.

Aaron Z

 

[Allee]

I found the owners manual but it looks like I need to find a confident tecnician to work on the adjustments. I don't have a CO2 meter nor would I know how to read it. I may succeed in getting our temperature stabilized after all. Any clue on how to contact a tech for the Aqua Star. I'll probably have to get on the horn and find one. Thanks for the help.

 

[aczlan]

I would start with the following:
1. Does it throw a code when it shuts off? If so, what is the code?
2. Watch the water pressure while someone is running water and see if it changes appreciably
3. Get a non-contact thermometer (such as Infrared Thermometer - Non-contact, Digital Thermometer ) and monitor the temperature of the output pipe.

The section I was referring you to:

HOT WATER TEMPERATURE FLUCTUATES /UNIT DEACTIVATED
• Unbalanced pressure in water lines Any restriction caused by the water heater in the hot water system can result in uneven pressures between the cold and the hot. In such cases when mixing cold water at the tap (manually or automatically through a mix-type shower valve) the lower hot water pressure may be overpowered by the higher cold water pressure in the building and cause the hot water flow rate to fall below the minimum rate required. A pressure balance valve will help to resolve this symptom.
• Temperature balance valves If the outlet water temperature is set too high, the heater can produce temperatures that are too hot. A temperature balance shower valve can automatically mix in cold water to reduce such hot water temperature. In the event of any temperature instability with the use of a temperature balance shower valve, refer to shower valve manufacturer's instructions for internal adjustment setting. Adjustments should be made to the hottest setting in the shower valve. Additionally the temperature control of the heater can be lowered to produce a more comfortable hot water temperature.
• Inlet water pressure is erratic due to fluctuating supply water pressure For installation on a private well system with the use of a pressure tank, the lowest pressure range setting
recommended is 30-50 psi (2.07-3.45 bar). The use of a pressure reducing valve after the pressure tank is also an effective way to maintain a constant water pressure to the water heater. Watts brand 25AUB-¾” or N35B-¾” pressure relief valves or equivalent are suggested.

Watching the system pressure and output temperature (along with looking on page 26 tor what the codes mean) should give you an idea what is happening and let you know if the tech is feeding you a line of BS.

Aaron Z

 

[Bikewanderer]

Up north here they work ok when the water inlet temp is 45ｰ or higher but on municipal water we get water temps in the range of 36ｰ from early in December on through the winter. The last time I looked at these when I replaced my water heater 7 or 8 years ago there was no readily available model that could handle a 2.5 gpm shower head at a 100ｰ rise.
Looking at the American data sheet in the OP it seems the biggest model (540) can give about 3.6 gpm at 100ｰ rise, although you are still not guaranteed an acceptable result because of inefficiencies that can creep in with pressure drop, scale buildup and an insufficient propane supply which cannot make vapor fast enough in the coldest temps to support a 199,000 btu burner. So if you're in the northern tier or northeast do your homework, know the coldest water inlet temp to expect, know the vapor capacity of your propane storage at the coldest temps your area experiences and know the scale tendencies or hardness of your water.


Ray

This has also kept me from doing it. 3.6 gpm isn't enough to wash dishes or the laundry and shower at the same time, so why bother? I have six people at home and soon to be a seventh. Our bathtubs are busy all morning and our water heater can barely keep up, but this would be worse than what I have now.

I don't think 200k btu will affect vaporiation rate too much unless it's a constant draw. I pulled 2.5M BTU off our 2000 gallon tank at work all day a few weeks ago and it never lost a lot of pressure. If it were a constant draw in cold weather on a low tank you MIGHT have issues.

 

[tkappeler]

See this


My system uses a dedicated return from the furthest faucet and a pump to keep hot water circulating at specific times of the day.

I have thought about this kind of re-circulating solution, however; I am going to use PEX and a manifold to distribute to the end points. There is no way to effectively recirc. Even if I create a loop for recirc off the manifold, I would only keep the line from the HWH to the manifold hot, all of the other lines are still cold.

 

[Bob77064]

That loop is a great idea, I wish we had one.

 

[WayneB]

I installed a Bosch FX 125 at our place in the mountains several years ago and we have enjoyed it. Key reason back then was for the ease of winterizing and with the old 40 gallon tank from time to time I would forget to turn it off and we would be gone for two weeks and heating hot water for no reason. With the on demand no problems what so ever. The real plus was getting to camp late at night and having hot water instantly. Also one could take a shower for as long as they wish and never run out of hot water.

We also have a larger Bosch On Demand Heater at home and really like it here too. The newer controllers are proportional and we have not had any problems in cold weather with the unit. I have kept propane records and we are averaging around $12.00 a month for hot water. I am using 100 pound tanks and have to haul them to get filled, but the price is cheaper than deliver cost so I continue doing it. Our primary source of heat is wood and we have hot water oil furnace backup but it is turned off and only used if we are going to be away for an extended period of time.