19 thoughts on “Tankless Water Heater 3 Things to Know”

  1. I'm working on a tankless water heater that doubles as a boiler. I have tried unsuccessfully to do the vinegar flush, and I'm being told that there may be an internal 3 way valve that isn't opening? How do I open this valve, or is there is some other issue with these heaters that I need to know about?

  2. As a self-employed HVAC technician, I would not recommend anyone that does not know this stuff and have the needed equipment, try to put in one of these tankless units. There is a whole lot of things that need to be done correctly before they will be safe to operate and work right. And then, after you go through all of that work to put one in correctly and it doe not work right, are you still covered? I bought the top-level, power-vented, Marey online to save money. It was less than 1/2 of what I could get ones that my local distributors handle. The unit would error out periodically, especially at lower temperature settings. The warranty requires the customer remove the entire unit and ship it to Marey to be fixed. …No F'In Way! So, I figured out what Marey did wrong, fixed it and all is good now. They did nothing to help me with this. The unit has a one-year full warranty and parts only for four years after that. In any case, you have to ship it to them to get it worked on. The issue with mine was the starting manifold pressure was too low and then when it would stage in the back section of the burner, it would sometimes lose flame signal due to a lower flame droop before the board would ramp up the flames (modulate) to get set water temperatures. The way this thing is built, it is not possible to get to that pressure adjust regulator cap without removing part of the gas valve possibly, or the entire burner box/heat exchanger assembly. So, I did what any real professional with 25+ years experience would do; pulled out my drill and bits. One carefully drilled hole, 1.5 turns of a screwdriver, and now the unit works perfectly. No thanks to Marey. Another important note: If you ever have to clean this thing out as far as the burners or heat exchanger goes, you will have fully disconnect everything and gut it down to the cabinet completely to do it. You cannot get the flame sensor or ignition electrode screws out either to service or replace them. Being in this game as long as I have, I was ready for this crap. I installed a 7-gallon electric water heater with isolation valves parallel to this tankless unit. If/when this unit ever fails again, we will be reduced, temporarily, to small-camper type status for hot water, but at least not be SOL. 🙂

  3. I want to see the smaller tankless that you put at each station. Under the kitchen sink for kitchen and dishwasher, in the bathroom for the shower and sink, one by the clothes washer. And show how they look inside. I'm trying to find one that reminds me of the one in Germany but that was 30 years ago and my memory isn't so great.

  4. I have 70 pounds of pressure at my house with the hot and cold water on full blast in my shower I have great pressure out of head but its only luke warm so I have to turn the cold water down to get the warmth I want and then I lose pressure……..I have a 75 gallon will an on demand fix my problem and give me the full 70 pounds of hot water out of the shower head ???

  5. what do you flush them with ? I have never seen any type cleaner for tankless water heaters.. I have had one at one of my properties on well water for over 7 years. the worst water ever..i have never flushed it..did not know about flushing..

  6. Okay…. so…if you have hard water… USE A WATER SOFTENER… IT DESTROYS EVERYTHING IF YOU DON'T… that means make sure you soften the water BEFORE you send water to your heater.. Whew! Okay.

    Shockingly, most plumbers don't do that… I wonder why? For those of you plumbers that do… point it out to your customers.

  7. Matt, is it required to install a Pressure Relief valve in a Tankless Heater, doesn't matter which State you live in? Recently, I noticed the hot water pressure is low when I turn on the shower. Could it be that the filter has sediment buildups inside? Thanks in advance for your advice.

  8. I believe you left out some important considerations. 1) The return on investment … the installed cost of a tankless water heater with a larger gas line (required in many cases) and more plumbing … you will need to install Unions before and after the tankless to send it back to the manufacture when it fails and it is going to fail vs a traditional natural gas water heater and any dollars saved on fuel. 2) Cost and difficulty of finding repairmen for a tankless water heater. 3) Manufacturer's warranties are so full of holes that they are not worth the paper they're printed on. Generally these are not wise investments.

  9. Does anyone have experience with the Seisco models? I've had an electric one for 17 years and it's great. With soft water I never get residue in chambers, also our water in FL in summer is about 80-85F coming in, winter 60 so the delta t is minimal.

  10. My water is heated by the recovery unit of the air conditioner, therefore tankless is not an option. Only 20 days or so a year are cool enough to not have air conditioning and then the heating elements come on.

  11. Another thing to add is that they can be very Loud when operating. My sister had to move hers to the garage because of the noise factor. Also that they add a lot of heat to the room they are in. Their garage can get uncomfortably warm when they are running in the Summer.

  12. Your conversation with Gary Klein, about hot water delivery systems was great too. It's a must watch. I've listened to it x3. You guys got me to rethink my whole approach. One small step for building science, one giant [systems thinking] leap for me. Thanks!

  13. some thing else to condenser is your gas btu in my area the therms in our gas is not great and a 199k water heater is not going to cut the 38 degree water in the winter. matt i wish you lived here in montana we could sure use your knowledge here is so hard to get the products that work here without giving up your left leg

Comments are closed.