Tankless the only option? - MultiHead Shower

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dimprov

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It shouldn't change your decision, but one possible gotcha I just realized: somewhere down the line one of your units goes bad and needs to be replaced. Not a problem now, but in the future maybe that model is no longer made. :eek: What then? Will the tandem/manifold controller work with a mix of different units? Or does the controller become the weak link that forces you to replace *all* your units? Ouch.

Any precedents, based on earlier models that are now "obsolete" and no longer being manufactured?

David
 
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Nicholas_ii

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Well, I have the units installed.
2 x R94LSi units in parallel with a 12-Gallon electric tank and Grundfos Recirc pump (retrofit style) hooked up. It's working ok so far. We'll so how it does one I get the shower in.

I had just one unit hooked up for a day, and turned on 5 faucets and a standard show head and saw the pressure downstairs fall enormously (my method of guessing at water pressure lost once I get my shower system installed). I'll try it today when I get a chance with the two units.

Question: Are you better off lowering the temp for both units and using less cold water mix or increasing the temp for both units and mixing more cold for pressure?
 

Jadnashua

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Probably running them hot and using less. Safety needs to be considered here as well - there's both a practical and safety limit on how hot the supply should be. Do you have a tempering valve at the outlet of the tankless systems?
 

Nicholas_ii

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I would doubt I have a tempering valve, as I don't know what that is.
I can control my tankless temps via remote, so I could only turn it up before showering.

I will have a thermostatic valve at my shower, which I believe will keep me from getting boiled.
 

Jadnashua

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Unless that is the only user of that hot water, anyone using hot could be at danger.

Basically, a tempering valve is used to set a maximum output temperature; if the hot inlet is above the set point, it mixes in some cold to 'temper' the output to the desired maximum, fixed level. They're required in some places, and you may actually have one. Some tankless manufacturers also require them, depending on design.
 

dimprov

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Just how accurate are tempering valves? Is it +/- 1 degree, +/- 5 degrees, +/- 10 degrees, or +/- 20 degrees?

I read that they are somewhat crude and can have large +/- temp variation, but I couldn't find any info beyond that. It would force you to set the water temp low enough so that the largest possible high-side variation won't scald you.

David
 

Blind Moose

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We are putting in a shower system similar to your set up Nicholas_ii. Do you have your shower in yet? Just wondering how your setup is working....
 

snd1232

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twin water heaters

I just wanted to comment that we have a MAAX shower with 8 in-wall heads plus an overhead and sprayer plus an additional 2.5 gpm shower head for a total of 10 heads working at any one time. Total waterflow is estimated at up to 20gpm. We have twin 9gpm ranni heaters all plumbed with 1-inch lines and we have never run out of hot water or had pressure issues, inspite of running off well water.




Would you expect that I would still have hot water pressure issues with 2 9.4GPM units? Practically, I don't think I would ever use more than 10, maybe 12.5.

There's no data for how 2 units in tandem work together.

It's a also a bit unclear how the recirculating system will play into affect here.
 
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