Do I need an expansion tank?

[Bubbles Galore]

I am going to segment our dog wash water away from our boiler using an on-demand style 20 gallon unit. There isn't enough consistency with the boiler and with cooler months coming around, I want to ensure I'm giving the best and most consistent wash around. The question is, do I need an expansion tank with this small of a unit? Thoughts?

Thanks!

 

[PaulLovesJamie]

I assume you're talking about between the demand unit and the dogs? If its a closed system, I'd put in the tank. If its open, its not needed. The basic principle is that water expands as it heats - there has to be somewhere for that extra volume to go, otherwise you build up unsafe pressure.

 

[car washing systems inc]

I am going to segment our dog wash water away from our boiler using an on-demand style 20 gallon unit. There isn't enough consistency with the boiler and with cooler months coming around, I want to ensure I'm giving the best and most consistent wash around. The question is, do I need an expansion tank with this small of a unit? Thoughts?

Thanks!

Most on demand heaters have a press relief, and since they only heat when they have flow i would think you would not need a tank. The systems we have done we did not need them but they where also just keeping a holding tank warm.

 

[Jeff_L]

Most on demand heaters have a press relief, and since they only heat when they have flow i would think you would not need a tank. The systems we have done we did not need them but they where also just keeping a holding tank warm.

but your holding tank had a pressure relief valve on it though too, right? i'm not certain if an expansion is required, but i would probably have one installed, or a press relief for safety.

 

[Bubbles Galore]

I'm not sure if this will help any, but this is the heater I am most likely going to purchase:

http://www.homedepot.com/Plumbing-W...splay?langId=-1&storeId=10051&catalogId=10053

Sorry it isn't a hyperlink, can seem to figure out how to do it from the advanced reply.

Thanks,

John

 

[car washing systems inc]

but your holding tank had a pressure relief valve on it though too, right? i'm not certain if an expansion is required, but i would probably have one installed, or a press relief for safety.

The system we did was an open tank, the heater should come with a press relief valve. If i get a chance i will look at the directions on the one we did and see what it says

 

[car washing systems inc]

I'm not sure if this will help any, but this is the heater I am most likely going to purchase:

http://www.homedepot.com/Plumbing-Water-Heaters-Point-Of-Use/h_d1/N-5yc1vZbqo7/R-100137155/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Sorry it isn't a hyperlink, can seem to figure out how to do it from the advanced reply.

Thanks,

John

That is just a hot water heater you will need a ex tank and relief valve on that, i thought you where talking about a instant hot water heater

 

[MEP001]

Have you considered an on-demand heater instead of a point-of use? Gas is typically more cost-effective than electric, and if you feed the remote heater with hot water it will only heat if that incoming water temperature is inadequate. You also gain the efficiency of not having to maintain any hot water.

 

[Bubbles Galore]

Have you considered an on-demand heater instead of a point-of use? Gas is typically more cost-effective than electric, and if you feed the remote heater with hot water it will only heat if that incoming water temperature is inadequate. You also gain the efficiency of not having to maintain any hot water.

My main concern with this was that the water temp minimum was going to be quite a bit warmer than I would want it to be. I suppose I could use a tempering valve, but it also seemed a bit cost prohibitive as well in comparison to less than $300 installed for the heater.

Thoughts?

 

[MEP001]

That does make sense; I'm just more of a long-term planner.