First Post: Navien tankless water heater question

[BillM18641]

I just purchased a home that was in a flood. Basement flooded and 4 ft on the first floor of a 2 story home. It was clean water, not muddy at all. In the basement was a Navien tankless water heater natural gas system. Model# CR-201A-NG. Electric was turned off to the house BEFORE the flood. I dried it out and blew everything out for 2 weeks, then powered it up with NO gas on as of yet. When i turn it on, it starts to power up then trips the breaker located inside the unit. I unplugged all the connectors on the circuit board inside and plugged them in one at a time till it tripped. It turned out to be the small circulator pump on the bottom left side. I can't find a replacement pump online anywhere. Any ideas? Is the circulator pump absolutely necessary for the function? I was thinking of taking it out and taking the cover off the pump to see if its rebuildable, or just still has water in the small motor. What do you suggest? Its a $2k unit and I'd hate to have to scrap it just because of that pump. Thanks. Bill

[Dana]

The -A version (rather than the vanilla CR-210) has a little mini-tank with circulator pump to avoid the "cold water sandwich" phenomenon, which is the slug of cold water that passes through the tankless before the ignition fires up. If you can plumb around the mini-tank you can probably just toss the pump and it should be fine (unless the controls are too smart, and figure out that the pump is missing. With the tank in the line the cold water sandwich may be exaggerated, since it has to purge the full volume of tepid-tank before the full-temp water would pass.

Have you called Navien America (or the local distributor?) This is a current model, and there SHOULD be parts stock available, but you'd never find the pump from a 3rd party online vendor. (Maybe in Korea you could- do you read Hangul? ;-) )

[BillM18641]

I looked on Naviens website and didn't see anything for distributors. I'll do a search online for local ones. If not, I'll call Navien and see if i can get just the pump from them. I was thinking about bypassing the pump but didn't even think about the mini-tank. I saw it mounted above the pump. Thanks And no i don't read Hangul. lol

[Dana]

I DO read Hangul (a little bit), but I'd still be way better off talkin' to the folks out in California. Good luck!

[BillM18641]

Thank you Dana. I went on Naviens website and shot them an email with my problem, asking where i can get a replacement pump for it. I'll let you know when they reply back with their answer.

[zl700]

There are 2 banks of DIP switches on the control panel. On the bank of 8 flip switch 4 & 5 up (on) then board wont be looking for the circulator till you replace it. The GFI is tripping because water is inside the windings. You cant repipe the inside around it but you can disable pump operation.

[SewerRatz]

Any water heater that has been in a flood is supposed to be replaced. The gas control valves can corrode and get stuck in an open position when there is no water flow and cause a real issue. Even if it was a tank power vent unit that costs 2K if it was in a flood it has to be replaced. No if's and buts about it.

[SewerRatz]

http://www.ahrinet.org/ahri+recommen...equipment.aspx

AHRI Recommends Homeowners Replace Flood Damaged Heating, Cooling Equipment




Contact: Monica Cardenas, Director, Communications
Direct: 703.600.0377


Arlington, VA (September 12, 2011) — Homeowners who have experienced flood damage are advised to take important safety precautions with regard to their home’s heating and cooling systems, according to the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), the trade association representing manufacturers of HVAC and water heating equipment.

“Standing water in a yard, house, or basement can damage a home’s heating, cooling, and water heating equipment, in ways that are not always readily apparent — putting families at risk,” said AHRI President & CEO Stephen Yurek. “We advise homeowners to play it safe and replace, rather than repair, flood-damaged heating, cooling, and water heating equipment.”

The association has compiled a list of heating and cooling equipment for homeowners to consider replacing if flood-damaged:

Gas Furnaces and Boilers: If there is any question whether flood water has reached a gas furnace or boiler, it should be checked by a qualified contractor. This equipment has gas valves and controls that are especially vulnerable to water damage from floods — damage that might not be visible. Corrosion begins inside the valves and controls, and damage may not be apparent, even if the outside of the device is clean and dry. At a minimum, this damage can result in reliability problems.

Electric Furnaces: An electric furnace consists of electrically heated coils, a fan to provide air circulation across the coils, and controls that include safety relays. As with a gas furnace, an electric furnace is susceptible to corrosion and damage from flood water, creating potential reliability problems or safety hazards. If there is any question whether flood water has reached an electric furnace, homeowners should have it checked by a contractor.

Propane Heating: Use extreme caution where there is the potential for propane leaks and have propane equipment checked, repaired and/or replaced by a contractor as quickly as possible after a flood. In every case, contractors must replace all valves and controls that have been in contact with flood water. The gas pressure regulator on a propane system should also be checked. This regulator contains a small vent hole to sense outside pressure. For effective gas pressure regulation, this hole must always remain unobstructed. During a flood, debris can easily plug the hole, causing dangerous malfunction or corrosion.

Radiant Floor Heat: With this type of heating system, electrically-heated cables or tubing circulating a fluid are embedded underneath or within the flooring material. The cables warm the floor, which in turn warms the room by radiant heat. If the floor becomes wet from a flood, it can weaken and perhaps crack and may need replacement. Both electrical cables and tubing can be damaged due to a wet floor. Therefore, a qualified professional should be consulted to determine whether the system can continue to be used.

Heat Pumps and Air Conditioning Systems: Split air conditioning and heat pump systems have power and control wiring between the indoor and outdoor parts of the system, and piping through which refrigerant flows through the system. If flood water has repositioned either the indoor or outdoor units of a split system even by a small amount, there is a potential for refrigerant leaks. The system will then require major repair or full replacement.

If the refrigerant system remains intact after the flood, the entire system should be cleaned, dried and disinfected. Homeowners should have a contractor check the indoor and outdoor units’ electrical and refrigeration connections, including all control circuits. The decision to repair or replace should be made after consultation with a qualified professional on a case-by-case basis.

Ductwork: If a house under storm repair contains a central forced-air system, attention should also be paid to the ductwork. A contractor will not try to salvage duct insulation that has been in contact with flood water, but will replace it because it is impossible to decontaminate. The contractor also will clean, dry and disinfect the ductwork itself. A thorough job will require disassembling the ductwork, but the silver lining is that such repairs will allow the contractor to seal joints in the ductwork and improve insulation to reduce heat and cooling loss.

Water Heating Systems: Whether a water heater uses gas, oil or electricity, if it was exposed to flood water, the unit should be replaced. A new water heater is a relatively small investment, and replacing it is fairly easy to do. If the water heater was more than five years old, the chances are good that a new unit will be more efficient, which will save the homeowner money in the long run.

In a gas unit, valves and controls can corrode. In an electric unit, the thermostat and controls can corrode. In both types, the insulation surrounding the unit will likely be contaminated and will be nearly impossible to disinfect. In addition, the insulation takes a great deal of time to dry and can lead to corrosion of the tank from the outside.

Even if water heater components have been cleaned and the unit seems to operate properly, parts may corrode in the future. Both gas and electric water heaters have a pressure relief valve that can corrode and stick after being exposed to flood water. Homeowners should be sure, therefore, to replace this valve as well.

Federal tax incentives for replacements and upgrades are available. For more information, visit http://www.ahrinet.org/Content/Feder...edits_896.aspx.

AHRI recommends that all inspection and replacement work on flooded equipment be performed by qualified heating and cooling technicians, not by homeowners. Qualified contractors are listed by zip code in the North American Technician Excellence (NATE) Contractor Locator at www.natex.org.

“While flood damage can be a very traumatic experience,” Yurek said, ” homeowners can turn misfortune into opportunity by considering new, energy-efficient models that will lower their future energy bills. They also should ask their local utility about available rebates for installing new, energy-efficient heating and cooling equipment, and a competent contractor will be able to advise homeowners about equipment eligible for federal tax credits or state energy rebates.”

[zl700]

No doubt Mr Ratz is correct in the eyes of the manufacturer.
However on tankless unlike a tank or furnace gas valve the 3-5 thermistors, 3 temp safeties and flue temp limit would stop a runaway tankless unit.