Tankless water heaters vs storage tank

[Eric H]

While I was at the ICA show last week I was looking at both floor heat boilers and water heaters offered by Huron Valley and CSE(Locinvar). Both companies seem to want to offer me a boiler with storage tank with an estimated cost of over $15000.
I didn't think to ask them about just using a wall mount tankless unit. I see Kleen-rite has a Takagi unit with an output of 500 gph for $1395. (I still need figure out my needed capacity for 3 bays, including rise)
Am I missing something? Is there $13600 reasons to go with the storage tank?

 

[rph9168]

In my area many washes have switched to tankless water heaters. Some use their old water heater tanks for storage.

 

[Earl Weiss]

While I was at the ICA show last week I was looking at both floor heat boilers and water heaters offered by Huron Valley and CSE(Locinvar). Both companies seem to want to offer me a boiler with storage tank with an estimated cost of over $15000.
I didn't think to ask them about just using a wall mount tankless unit. I see Kleen-rite has a Takagi unit with an output of 500 gph for $1395. (I still need figure out my needed capacity for 3 bays, including rise)
Am I missing something? Is there $13600 reasons to go with the storage tank?

My floor heat does not have a storage tank, but the water for the bay supplies does. I would like to see operational cost comparison. I would think that for the floor heat, the floor heat piping is the tank. Lets face it, if you need to have it on, by the time the warm water circulates thru the system, it needs to be reheated after it returns in order to do the job. On the other hand, for the bays it may cycle less by storing the water in an insulated tank with a circulation pump. Iw ould look at the water heating costs by seeing what I am paying for natural gas when I don't run heaters or floor heat and try and project what the percentage savings might be with a tank versus tankless. If you guess you can save $100.00 a month it's not worth it. If you guess $500.00 per month savings (doesn't seem likely) in operational costs, then you might consider it.

 

[Earl Weiss]

In my area many washes have switched to tankless water heaters. Some use their old water heater tanks for storage.

Wouldn't you need some sort of recirculation system since overnight or on rainy days the water in the tank would go cold?

 

[rph9168]

The ones that I have seen using the old tank do have a recirculation system that I believe is contolled with a thermostat. Most do not use a storage tank since the tankless heaters are able to keep up with the demand.

 

[Waxman]

Eric H?

Tankless is the way to go. Even a hippie like me knows that! Look at Dirt's setup.

 

[bigleo48]

Eric,

I have 6 tankless water heaters. 4 are for my 8 bay self-serve (floor heat, hot water, room heat). They are Rinnais, about 200000 btu each and I have a sperate glycol circulation system with a heat transfer coil to heat the glycol.

My stand alone IBA has 2 Kiturami world boilers (100,000 BTU each). The are dual boilers (hot water & glycol for the floors), so they have a small tank for the glycol built right in...very cool.

As you know, I'm in Canada, so very cold at times and they work great! I don't own a storage tank and in the summer months when it rains, nothing is heated and no tanks!

Wouldn't do it any other way and I am currently looking at replacing my hot water tank at home with one.

Big

 

[boywonder]

I have 2 high efficiency boilers for my floor heat. They could also heat water as well. The reason for needing a storage tank is for indirect water heating. The heat exchanger in a high efficiency is stainless steel. Most manufacturers don't recommend and most times void your warranty if you ran straight water through it. The only thing they recommend running through your boiler is water/gycol mix. I know with ours they need to be mixed 50/50 and be within a certain point on the ph scale. Im currently looking for hot water heating, but Im not at a need point yet.

 

[Whale of a Wash]

I was with Eric looking at both systems. Eric has 1M btu floor heat. While we were looking at Lochinvar, the guy said he could probably use alot smaller system, as it was 99% effic. I think someone bid the high number on the same size. I was thinking he could get by with the 500-600K at about $7500 for floor and bays. The storage was to separate the different systems. I have 36 palomas but they are only 80% eff. I think the 20% increase in efficiency,
is a major savings, if he doesn't Super-Size it.

 

[mjc3333]

I also asked Huron Valley about the super high efficiency water heaters and floor heat. They claim 98-99% efficiency. My current setup uses the hot water sink itself as the holding tank. If I was going to go with the high efficiency boiler, I would continue to use my sink as the holding / recirculation tank.

I had a system that had it's own holding tank with the output going to the hot water sink, then gravity fed to the bays. It was horribly inefficient. The water was always cold until 2 or 3 bays were used each morning.

Even though the instantaneous heaters are still only 82-83% efficient, having hot water only when its needed seems to make the most sense. Fred Deal from Huron Valley said I could use their 98-99% heater in the same fashion. The only problem would be the super high cost. It would take years to justify the extra cost. By then, the heater might need to replaced anyway.

Tankless instantaneous heaters are the way to go. You just have to make sure you have enough flow. Most tankless heaters have a flow reduction valve when heating demand increases. Tying 3 or 4 together would solve that problem. You have to check the delta on temp. rise for each unit. If you want to go from 35 F to 120 F at 25 - 30 GPM you would need multiple units. Still, at $1300 + or - per unit times 3 or 4 it still cheaper than $15,000.

 

[bigleo48]

. You just have to make sure you have enough flow. Most tankless heaters have a flow reduction valve when heating demand increases. Tying 3 or 4 together would solve that problem. You have to check the delta on temp. rise for each unit. If you want to go from 35 F to 120 F at 25 - 30 GPM you would need multiple units. Still, at $1300 + or - per unit times 3 or 4 it still cheaper than $15,000.

As discussed in an earlier post, I have disabled my flow reduction valve (disconnected them when they were fully open). That way if demand exceeds the ability of the boilers to keep up, your water will get colder but not restrict flow (and starve the pumps).

Also keep in mind that every boiler requires about .5 GPM to fire. So if you have 4, then 2 GPM to fire. Not usually a big deal but if you have various circulation pumps in the system, they need to draw more than the minimum to work.

Big