Water heater gremlins strike in the dead of night

[wash4me]

Westinghouse 50 Gal. Ultra-High Efficiency/High Output 10 Year 76,000 BTU Natural Gas Water Heater this is the same brand but in the residential line. You could install this and the cold water valve if the tank gets low. It would work flawlessly without worrying about pressure loss, bigger gas line recirc pumps etc. $2000 at home depot looks like.

 

[OurTown]

Westinghouse 50 Gal. Ultra-High Efficiency/High Output 10 Year 76,000 BTU Natural Gas Water Heater this is the same brand but in the residential line. You could install this and the cold water valve if the tank gets low. It would work flawlessly without worrying about pressure loss, bigger gas line recirc pumps etc. $2000 at home depot looks like.

With only 3/4" hookups there would most likely be flow issues plus 76,000 btu is pretty low. Also it takes up floor space which will be an issue in the near future.

 

[OurTown]

I've also been thinking about just looping the pipe to the heater and turning on a recirc pump with a flow switch. The heater itself would control the water temp, and with it just running a loop in the plumbing there would be no supply issues.

I've thought about a loop just so there's no supply restriction to the tank, it will just run cool or cold if the heater can't keep up.

Mep can you give me some more details about your idea? I can't exactly picture how it would be set up but sounds interesting. I'm thinking of plumbing our presoak hydrominder cold.

 

[MEP001]

I realized after I saved the image that I'd probably reverse the pump flow so the circulating isn't against the flow to the tank, but the idea is the same. Straight pipe to the tank means no supply issues, no need for a second fill valve. Any failure in the system won't affect flow.

 

[OurTown]

Interesting. The flow switch turns on the pump and runs until there is no demand anymore I assume. How would you set it up with two heaters that each have 3/4" fittings feeding a 1" pipe? Two pumps and one switch?

 

[MEP001]

I had never considered more than one heater. I suppose with a big enough pump you could recirc through two heaters, but two can supply at least four bays without a problem.

 

[JGinther]

I have seen many loops like this for radiant heat systems, but never for domestic or "car wash water". I'm confused. Where would the aquastat go? Or the flow switch turns on the pump and the heater runs, but NOT in "recirculation mode"? As recirculation mode goes until the inlet temperature is up to setpoint... But then, I think you would always get cold water in the tank first, then, as long as the float maintained equilibrium mode and steady flow, the water would start heating up and get warmish...

Seems easier to just fill cold, then recirc the tank with the heater.... If you have a second heater, put it as pressurized supply...

 

[MEP001]

I agree it would be easier to recirc from the holding tank to the heater, but I just feel that's less efficient. The whole idea of a tankless heater is obviously to avoid heating stored water.

I do like the thought of one heater to heat/maintain the tank as you said and one inline on the plumbing like in my diagram. In such case I'd start the tank heater when a bay timer starts, and hopefully if they begin with tire cleaner and/or presoak the tank water will be hot when they select high pressure.

Realistically, I wouldn't put the loop on such a small length of the plumbing like in my diagram, I'd use a much larger pipe than necessary to act as storage and run as much length as possible. Yes, you'd get cold in the tank first, but it heats up surprisingly fast. I wouldn't use an aquastat if the heater works the way I think it would - it should reduce its output as the water heats up and, once the tank is filled and the flow switch opens and kills the pump, will stop heating.

 

[OurTown]

I really appreciate everyone's help and like Mep's idea but it might be too complex especially if I'm going to use two heaters. He should try it and get back to us. We really need to get this done so I'm thinking of simply using two 199K heaters run parallel to the 1" line to the tank and a low level cold float valve. It makes sense in our situation when factoring in cost, floor space and pump feed reliability. It would also be easy to take one out of service without disrupting much.

 

[JGinther]

I wouldn't use an aquastat if the heater works the way I think it would - it should reduce its output as the water heats up and, once the tank is filled and the flow switch opens and kills the pump, will stop heating.

That is the recirculation mode I was talking about. Recirculation mode requires an aquastat on all the models I have seen. Maybe there's a way to fool the heater, but as far as I know, the computer only knows how to handle dynamically increasing water inlet temperatures in recirculation mode. Normally, when the heaters are in recirculation mode, they require the aquastat to wire to either a heater, or multi-unit controller. That controller then provides the logic and control on the pump so as to stage the fuel and use up heat within the exchanger.

 

[OurTown]

Can the Jobe Topaz valves be mounted through a hole in the tank without going into a pipe thread bung that is welded in? It looks like they have a flange, seal and nut unlike the other float valves. If that is the case then is the standard $75 valve okay for this or should I get the $207 Industro high temp version? There is also the larger bung welded into the tank but it looks like a 1 1/2" and only on the outside of the tank meaning the taper is from the outside. Is that some sort of overflow or vent?

 

[OurTown]

I see that the standard valve is good for 140F so maybe that is the one for us.

 

[MEP001]

I really appreciate everyone's help and like Mep's idea but it might be too complex especially if I'm going to use two heaters. He should try it and get back to us.

I probably will at some point. I've been working with a guy who has an underperforming wash, and I'm sure not having hot water is part of the problem. He wants to get it going but can't justify enough heating capacity to run the whole 6-bay, but if we can heat just the soap for around $1200 he'd be willing to do it. So I can't just plumb it inline to the tank or if he gets busy he'll be running out of water. A household heater was our first idea but it will have such a low recovery rate it won't keep up with two bays, and two of them will cost more and have less heating ability than one 199k on-demand unit.

 

[OurTown]

Another new thread on here about going tankless has prompted me to update this one. We decided to replace the tank and stick with the boiler for now. The tank we are going with is the 60 gallon stainless steel Lochinvar SJS060.

http://www.lochinvar.com/_linefiles/LTS-01.pdf

The old tank was 80 gal so I realize the boiler won't run as long per cycle. In a few months or so when we need the room for the big remodel then the boiler might be replaced with one or two tankless type water heaters mounted on the wall. This new tank is only 36" tall so it can be put on a stand above the floor heat manifold area (where our boiler is now) to save some space. The issue is the new tank has an aquastat dry bulb well that is only 3/8" diameter and our aquastat bulb is 1/2". Our aquastat is a Honeywell T678A and wondering why the wiring has to be so complex? Is it because our boiler has a two stage gas control valve and that is why the extra switch? Can this boiler just be ran in low or first stage and so we can buy a less complex aquastat with a 3/8" bulb?

https://customer.honeywell.com/resources/techlit/TechLitDocuments/60-0000s/60-2200.pdf

 

[JGinther]

Is it because our boiler has a two stage gas control valve and that is why the extra switch?

yes

Can this boiler just be ran in low or first stage and so we can buy a less complex aquastat with a 3/8" bulb?

It can, but you don't use the whole boiler then. The output is much less.

 

[OurTown]

I'm thinking that either the boiler never goes into high or it never goes into low because it always sounds the same when firing up and running.

 

[MEP001]

I used to install Teledyne-Laars boilers which has the dual-stage thermostat in a well in the boiler manifold. The units were just switched on and off with a simple remote aquastat in the tank. The vendor recommended that the one in the boiler be left at 140° since the tankstat would be set lower, so the boiler would always run on high.

 

[OurTown]

I'm trying to understand what we have right now. Why have a two stage boiler? When would the second stage kick in? Would it be when there is too much differential between the water temp and it's setting? If that is the case then it might only kick in when the stat would be turned up lets say 20F more than it was set for.

 

[JGinther]

2 stage boilers are there for efficiency purposes. Boilers are terribly inefficient when they first turn on until draft is established. And if you can get to set point without using as much fuel - you get better start efficiency and use less fuel. If its keeps loosing the game to get to setpoint (water temp gets even colder), then you have a second gear to grab.

 

[OurTown]

2 stage boilers are there for efficiency purposes. Boilers are terribly inefficient when they first turn on until draft is established. And if you can get to set point without using as much fuel - you get better start efficiency and use less fuel. If its keeps loosing the game to get to setpoint (water temp gets even colder), then you have a second gear to grab.

That makes sense. Since we do not use much hot water then I bet the second stage has never kicked in.