What's Your Experience with Rinnai Tankless Heaters

[blurdgman]

Please give me insight to using Rinnai tankless water heaters in replacement of old Raypaks. Do they require a lot of service. Has anyone decided against this brand for any reason? I'd be converting two 6 bay SS's. Would plan 3 units for hot water.
Thanks for your help.

 

[bigleo48]

Blurgman,

I have four 180000 BTU commercial units. They work fine and no real issues so far. However one issue they have is control when using multiple units together. As you may know, it takes flow to get them working (.5 gallons per unit, so 1.5 gallons for 3 units).

Their control is supposed to regulate the flow through each unit so that if you draw less than 1.5 gal, only one will fire and the flow valve in the other two stay closed. This is done by measuring the temperature...if drawing less than 1.5 gallons and the sensor will measure low water temp and close flow valves accordingly to maintain temperature.

The problem occurs when you are drawing so much water that the heaters cannot maintain temperature, so the valves start closing and you wind up starving your pumps. To get around this you disconnect those valves in each heater. However you will not get any heat unless you have more than 1.5 gal of flow and if your heaters cannot maintain temp, the water will get colder...but at least you are still running!

Hope this makes sense...Big

 

[blurdgman]

Thanks Big Leo. How many bays do your four Rinnai units service?
I was thinking 3- 198000 btu/hr units for 6 bays in the Norheast.

 

[Reds]

Leo, do you know how to disconnect those valves? If so could you let us know? Thanks

 

[Jeff_L]

I thought I read another post about this where someone suggested taking your heavy use bay and your least used bay and run them off the same tankless. Then keep doing this until you're out of bays. Would that thought process still be valid?

 

[bigleo48]

Reds,

I did it years ago and the boilers have changed somewhat, You can follow the water flow through the boiler (and with your manual) to find the flow control valve and disconnect the wires (connector likely). Make sure it is fully open when you disconnect. Then test will lots of flow and high heat setting and make sure the flow is not restricted when the boiler has trouble supplying the heat.

Jeff,

I'm not sure I understand your question. My point was that in a carwash application, a lower water temp is acceptable, but water loss is not. So by disconnecting that valve, you ensure flow not temperature.

Big

 

[Jeff_L]

I'm not sure I understand your question. My point was that in a carwash application, a lower water temp is acceptable, but water loss is not. So by disconnecting that valve, you ensure flow not temperature.

Sorry, my question had absolutely nothing to do about the valve, more on best practice when designing for tankless use. I think what I said is pretty logical, not really sure why I posted. That's what I get for typing before drinking a cup of coffee.

 

[mac]

Because I live in FL I have not needed to look at heaters of any kind. What I have found though is that the companies that advertise a lot for homeowners, usually cost a lot more than commercial operations. Kinetico is a good example. They advertise on the radio a lot about using no electricity. Big deal. Their systems that I've seen or had quoted were about three times what a regular system costs.

 

[MikeV]

The tankless systems do cost more than a tank type water heater, but over time will save a lot in fuel useage. I swapped out an old raypac for 2 Takagis about 6 yrs ago, cut my fuel (gas) bill by well over half. I use 2 tankless heaters for 5 s.s. bays and an auto. All high pressure on the s.s.bays is heated and the presoak on the auto. I have heard that the Rinnais are very good and dependable.

 

[washnvac]

I have had two in place for over two years. Not one problem. I installed mine a bit different than the other posters. I installed only one heater for a 9-bay, and one heater on a four bay. Instead of direct feeding, I am running a closed loop with a small circlualtor and a boiler coil in my hot water reserve tank. This way, I only needed one heater for each location. Yes, I am maintaining some hot water--about 35 gallons for the 9 bay, and 12 gallons on the 4 bay. This way you do not have to work about the feed and flow issues. Even on the nine bay, I never have more than four pumps running hot water. I maintain the reserve tank at 115-120, with the heater set a 140. In the Winter when it is busier, I do turn the heater setting to 160 or 185. Only occassionally does my reserve tank fall below 110; and if it does it is only for a minute or two. This is just a different way to install it. I guess the disadvantage will be if for some reason that one heater fails, I will have no hot water.

 

[Reds]

Washnvac: I am using the same type system and am having trouble with circulating the water thru the heater (circulating thru 3/4 line - 4' of head). I am using the pump recommended by Rinnai for my application and have replaced the pump to make sure that I didn't have a bad pump. What are you using for a circulator pump? Make and model of pump would be helpfull. I am suspicious that my heater is defective (Rinnai is about 6 mo. old) and the internal valve is not letting water thru.

 

[washnvac]

I know that you need to move at least 3 gpm for this type of application. Did you calculate the head for the pump you are using? In other words, does your pump give you 3 gpm with the head that you have? Also, check the inlet strainer to be sure there is nothing clogged in it. I know my pump is a Grundfos. I will get the model number on Friday for you.

 

[bigleo48]

Yeah...you gotta clean those screens out on a regular basis or the performance of the heater goes down.

I purchased a designed system with the floor heat module (uses Grundfos pumps). So it all works together well.

Big

 

[washnvac]

Reds...I finally got that model number for you. It is a Grundfos UP 26 99 BF;
p/n 52722347

 

[Reds]

washnvac -- Thanks for your help.

 

[ToFarGone20]

3.5 years

5 Rinnais running 6 car bays and two truck bays. I have a 10 gallon insulated tank they pump into...from there they flood into the manifold that feeds my pumps. I have float switch in that tank wired to an asco valve that allows city water into the heaters. Water in tank starts to fall and on come the heaters. I have never disabled a valve on these machines....I have adjusted my float a few times in the tank. I have a sixth machine I thought I would need but I now use it to keep the temp up in my auto hot water tank during the winter. It keeps the Raypak from coming on (until we get busy and then it cuts in). I also use the sixth to make presoak...Its plumbed right into the hydrominder and flows into an isulated tank. I have found these to be tough and reliable units.

Should be a picture of my setup somewhere on here.

A.J.

 

[ceulenfeld@austin.rr.com]

water heaters

I had a Locknivar 360,000btu boiler with a holding tank. My Locknivar developed a hole in the copper and now I need to replace it. I have a plumber who wants to install a tankless, but keep using my resevoir tank. He wants 3000 labor and Materials. A new Locknvar 360 is about $3000.00 by itself. I have 4 bays down in TX where the incoming water temp, even in the winter is always 80*. My pumps are rated at 4gpm. The tankless the plumber wants to put in is rated at about 12 gpm with minimal temp rise.
Can you advise?

 

[MEP001]

Since you're using it with a storage tank, the flow rate of the tankless heater used as a circulating heater is irrelevant. The worst that might happen is the water might not stay hot, but as long as you have cold water rinse and other functions for customers to use you likely won't have a problem with 80 gallons of stored hot water and four bays. Supply of water won't be affected by switching to tankless (but neither will overall efficiency).

 

[MikeV]

$3000. sounds a little high just to install a water heater. I installed mine myself...no big deal. I use one Takagi, a 35 gal storage tank and a cold water mixing valve to regulate the temp to supply all the high pressure water for 5 bays and the presoak on the auto. Never have run out of hot water.

 

[cherokee235]

I had a Locknivar 360,000btu boiler with a holding tank. My Locknivar developed a hole in the copper and now I need to replace it. I have a plumber who wants to install a tankless, but keep using my resevoir tank. He wants 3000 labor and Materials. A new Locknvar 360 is about $3000.00 by itself. I have 4 bays down in TX where the incoming water temp, even in the winter is always 80*. My pumps are rated at 4gpm. The tankless the plumber wants to put in is rated at about 12 gpm with minimal temp rise.
Can you advise?

Wow, that seems high. Get the install manual from Locknivar and install this yourself. From the manual it looks pretty easy. Some sweating copper will be required. Unfortunately, even though you can follow the install manual as well as your $3k plumber, in a commercial application I doubt you can obtain a permit. I'm not advising bootleg plumbing, just telling you this is not rocket science to follow the mfg install manual.
Good luck