Question about Rheem Tankless Hot Water Heater Rtg-74pvp-2 7.4 Gpm

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I am having problems with the down draft coming into my tankless h2o heater and freezing the water in the heating chamber. The damper inside the heater is closing properly. How do I reverse the draft to get it to **** air out instead of bringing in air? The water heater functions normal until it freezes. the water heater is a richmond rmtg-74pvn

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There is a backflow damper that goes in the flue you can buy. Do you have a 3 or 4 inch vent? Takagi makes a 4 inch one.

Posted on Jan 23, 2009


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My water heater shuts down in cold weather. How do I fix this problem

Add tempering tank.
Tempering tank made from old tank-type water heater, or small tank heater will passively heat incoming water.

This works because tankless can only raise temperature so many degrees. If water is very cold, tankless cannot keep up, so the sensors shut down the unit.
Passively preheating water... or using a small tank connected to power can preheat water enough so tankless works.
Also delime tankless each year will help remove natural scale that builds up inside tankless heat exchanger.


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Feb 13, 2015 | Water Water Heaters

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How do I bypass the Honeywell damper assembly on the rheem G100-200

Damper is built into gas water heater.
The damper is part of the firing sequence, and required to draw air into combustion chamber.

Replace gas water heater?
More troubleshoot resources.


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Sep 30, 2014 | Rheem Water Heaters

1 Answer

No condensate coming out of the condensate drain just blows out air

Call Rheem and they will recommend calling installer since tankless computers are non intended as do-it-yourself.
If condensate drain is blowing out 'air' do not forget this air is deadly poison CO gas and will kill you, first giving you a headache that goes away when you are out of house. Remove affected people from home and put into fresh air and lay on side, never on back or they will suffocate. Call 911 immediately and most will recover.
Copy following link for resources and required maintenance for tankless computers that heat water: scroll down to venting and manuals and review each to check how vent lines are set up, and that condensate line is set correctly. However this information is NOT guaranteed to match each model made by Rheem as they advance their product marketing strategy to exclude as much safety information as possible for do-it-yourselfers.
Condensate lines can clog over time. Clean line with compressed air, and soak in clorox, and swing around overhead to remove anything inside line. This line contains bacteria so do it in neighbor's yard.
Not all conditions produce vent condensate. Condensate might not form in vent line if weather is dry and the vent has good draft. But later when conditions change, condensate might begin flowing.
Condensate is caused from burning hydrocarbon fossil fuels in any gas appliance. But problem is bigger with tankless since these appliance consume so much fuel per heating event since tankless are required to heat water rapidly as water passes by in a pipe. This is why tankless require larger incoming gas line, and larger vent line made from specific materials for the vent.
Among the long list of poisonous by-products being vented outdoors into the air our planet breathes is acidic water vapor. If conditions are such that the vapor condenses before reaching outdoor, then the acidic water gathers in the vent line and rolls back toward the tankless computer, and goes down into the condensate drain and then down into your pluming drain where it can corrode pipes and add acid by-product to other environments.
If the acidic water is allowed to fall back into tankless heat exchanger instead of down condensate drain, then eventually it will chew a hole through the special nickle alloy heat exchanger (imagine the hole it will chew through household drain lines), and the surprise will not be evident for a few years until leak develops and the tankless exchanger must be replaced at great expense, plus repairs to shorted motherboard and electrical sensors.
Just don't install tankless computer water heater is best solution for myriad of problems, maintenance, and expense of owning a device that must immediately monitor incoming and outgoing water temperatures and flow rates, incoming gas flow rate and pressure, outgoing vent flow and pressure, interact with a remote control device, while monitoring burn rates and combustion temperature using a computer motherboard that is not protected from line interference or power surge, etc
Just install tank-type heater:

Aug 18, 2013 | Rheem RTGH-84DVP Condensing Tankless Water...

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How do you insulate a tankless water heater for winter

If you have tankless electric, it can simply be insulated... but tankless electric are seldom mounted outdoor.
Service bulletin says: "the only way of assuring protection is to completely remove the heater during those times the area may experience freezing temperatures.

There are tankless with built-in heater for exterior installation.
Check your manual, or add a comment with specific model number and maybe I can find the information.

Here's why they install tankless outdoors: Because tankless burn more fuel per gallon of hot water. This requires larger gas line and larger vent pipe than typical tank-type gas water heater that is usually installed indoors.
They install tankless outdoors, so there is no need for expensive vent pipe, and because there is ample incoming air to support combustion.
So if tankless does not have factory-installed internal heater, then the unit can freeze easily when the combustion draws in cold air.
Of course you can put heat-tapes on the pipes but the heat exchanger inside will quickly freeze during periods when hot water is not being used, and combustion is not taking place.

You can move the tankless installation inside and use correctly-sized vent and intake pipes directly through the wall. This will generally protect tanklesss from freezing if room is heated adequately.

Sep 26, 2012 | Rinnai Webstone The isolator EXP tankless...

2 Answers

Error code C7 13

Before calling service technician, open following links for troubleshoot resources including Rheem chat, and Rheem contact, and possible product manual:

C7 13 might be bad flow control valve.
While the tankless is down, I suggest also catching up on general maintenance such as cleaning the combustion chamber and burner parts, checking vent drain line, and cleaning water filter, and de-liming the heat exchanger.
Some resources are shown following pdf:

Sep 23, 2011 | Rheem Paloma Tankless Water Heaters...

1 Answer

Our tankless water heat will not heat the water-it won't ignite

Question posted under Boasch tankless. Model number not known.
Before calling service technician, open following link for Bosch troubleshooting resources, including phone and contact for Bosch, error codes, and possible manual, plus hours of reading and research:

As you know from reading manual, tankless water heaters require yearly maintenance by trained service technician, or by homeowner. This action would check gas and pressure, venting draft, condensation drain, burner and combustion parts, igniter and-or pilot light, electrical connections, air intake and general condition of plumbing.
Problem you describe does not include error code.
Open following link for possible help with general plumbing problem:

Add a comment with model number that appears on side of unit, and I can directly locate possible service bulletins and further troubleshoot resources available at Bosch for possible do-it-yourself diagnosis and repair.

Sep 02, 2011 | Bosch & Tankless LP Hot Water Heater

1 Answer

When the temp. dropped below zero outside the cold air coming down the exhaust froze the water heater. it is installed in a heated basement but there is no way to keep the cold out of the exhaust. any...

You can look into an electric flue damper. It must be tied into the heater controls so the fail-safe is that the heater will not operate unless it senses that the flue is open.

Feb 09, 2011 | Bosch & Tankless Water Heater

1 Answer

What is the minimum GPM's for a Rheem tanklers water heater to work? I can only run the shower by itself. Also can I install an outdoor tankless Rheem in an area where it gets down to -10 degrees F ?...

Rheem makes a number of tankless models

They make a tankless 95 outdoor series

The 95 outdoor series spec sheet says .4 GPM minimum activation and .26 GPM flow to keep burner activated. The colder the incoming water, fewer users can take a shower at once.
The .4 GPM and .26GPM numbers are fairly typical for tankless units.
These numbers are good when the unit is new.
After a few years the number may be different because the tankless is a high-tech machine with sensors that are susceptible to particulate in the water, and susceptible to perfect-functioning of other parts in the machine.
The outdoor series spec sheet says the tankless is good to minus 30 F.
But remember that's when the unit is new.
Outdoor tankless water heaters have an electric heater that keeps water pipes inside the unit from freezing, as long as electricity is ON.
If electricity goes off, the house stays warm inside for several hours.
But a steel box located outside would get cold immediately without electric heat.
The electric heater adds standby cost to operational expense.
The tankless has a heater, but you still have to protect the incoming and outgoing pipes.
If your incoming water is very cold, the tankless heater may not be able raise the temperature fast enough to give two showers -or- even 1 shower depending on age and efficiency and capacity.
You can add a tempering tank located in naturally warm area that passively pre-heats incoming water before it enters the tankless burner.
It might be best to locate tankless inside the house >> and use direct vent through the wall for both incoming air supply and outgoing vent gas.
If incoming air is taken directly from the living space, then tankless will draw air into the house through cracks and around doors.
A lack of sufficient air, or poor air quality can cause the burner to shut down.

When buying a tankless, read the spec sheets and really ask questions about everything you don't understand.

Oct 24, 2010 | Rheem RTG-53PVN Indoor Natural Gas...

1 Answer

No hot water

Aquastar 1600H NG Natural Gas Tankless Water Heater Bosch AquaStar Model 1600H NG Natural Gas Whole house tankless gas water heater, 117,000 Btu input, natural draft with hydro-generated ignition. Provides endless hot water for one major application at a time . Can replace 40-gallon storage tank water heater. Optional Accessory: Model AQ1- Power vent with built-in... More freeze protection when venting horizontally. Capacity: 1 to 2 Bathrooms Dimensions: 8.75D x 18.25 W x 29.75H Weight: 40 Max GPM @ 45F Rise: 4.2 Energy Factor: NG .80 LP .84 Minimum Input: 28,000 Maximum Input: 117,000 Vent Size: 5 Gas Connection: 3/4 Water Connections: 1/2 Warranty: 12-year warranty on heat exchanger, 2-year on parts Features: Endless hot water Can save up to 50% off utility costs annually Perfect for one major application at a time No standing pilot, hydro generated

Mar 01, 2009 | Bosch 1600H-NG Natural Gas AquaStar...

3 Answers

Power vent tankless heater has a down draft

I got a dryer vent kit (Alum) took the extension pipe off and cut the center hole open a little and slid it over the existing elbow. Now when the heater turns on the little flap opens and when the air flow stops the flap closes stopping the air coming down the pipe.

Jan 16, 2009 | Rheem Tankless Hot Water Heater...

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