Is DHW from Mod/con without Indirect tank adequate for 2?

kevin coppinger_4

at a time yes...more than that probabaly not unless you cusomize the flat plate heat exchanger to a very large one...Super stor does make a 30 gallon low boy water heater to work w/ any of the units you have...put a good mixeing valve on the tank and it should help....kpc

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Yeshwant

Is DHW from Mod/con without Indirect DHW tank adequate for 2?

Only two adults in our house. Do we need an indirect DHW tank or can we make do with the gpm that the mod/con itself would supply on demand? Laars Mascot says it can supply something like 3.6 gpm at (they say) 140 degrees (80 degrees rise), while the Vitodens 6-24C provides 2.1 gpm. The Munchkin Contender requires a tank.
At the most there might be two low-flo showers or a shower and a dishwasher or frontloading washer running at the same time, but mostly only a shower. And what about filling a tub? Trying to save space and install in living space, hence would prefer to avoid a big tank.

ALH_4

Combi

Just make sure you will not use more hot water than what it can supply. Combi boilers are made for situations like yours.

I highly recommend putting a tank somewhere in a closet or otherwise nearby. The tank gives you a lot more flexibility to adjust the amount of hot water you can deliver than the combi boilers will. Crown Boiler has a Megastor 26 that is very small. Plus tanks will not foul the way the heat exchangers in the combi boilers can.

It's not that combi boilers dont work, but floor space has to be very short to make it worth the trouble of using one in my opinion.

Brad White_9

You answered your own question... :P

If you have two low-flow showers and a dishwasher or front-loader running at the same time, that is likely to exceed the demand; add up the GPM flow rates and see. If you have 2.5 GPM shower heads using 2.0 GPM hot water, you are going to have cold showers real soon even without laundry.

Mod-Cons with built-in DHW are great for in-law apartments, single users and grunge rockers who do not bathe much anyway.

I would get an indirect and be done with it. You will never run out and not have to play the ration game and bargaining with your spouse as to who gets to shower first.

In my opinion, if you yourself decide to go with on-board limited DHW production and your wife finds out that you made that call, the cold showers may be of benefit to you after all.

Mike T., Swampeast MO

Two simultaneous showers @ 1.5 gpm (estimate of the "hot" flow to a 2.5 gpm head) shouldn't be any problem unless both like really hot showers. As long as it's not a big tube with 3/4" fill valves, utterly no problem for a bath. Clothes washer and dishwasher filling at the same time might be a bit of a problem as solenoid valves can move some pretty hefty gpm, but I wouldn't be very concerned. Many dishwashers now heat the water to the proper level (including quite high for the final rinse) and front-loading clothes washers [all] seem to actually measure and control the water temp.

hr

I installed a Laars mascot

in my in-laws home. Older retired couple, nice folks

The Mascot easily supplies DHW for a shower, tub fill, washer, etc. One thing at a time generally although it will run the dishwasher and wash msachine at the same time.

Keeping the HX clean will be important. I suspect hard water wouldscale the small FP HX after a while. Pipe it with a couple of those neat Webstone iso-flush valves for easy cleaning.

Remember incoming water supply temperatures change the output capacity. Read the GPM output at the correct temperature rise so you are clear with your actual GPM flow.

hot rod

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Glenn Sossin_2

shower together

Now if the 2 adults shower together, that might help the load some.

Uni R_3

Get a small tank...

More reliability, simplicity and performance.

Mad Dog_2

Andrew makes great points and

don't forget...one of the nice features of using an indirect is that you can PUT IT out of the way,i.e., mount it up on the ceiling, wall crawlspace. Mad Dog

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Yeshwant

Wow, this site moves fast! I posted yesterday and already my post is buried. Cool.
Anyways, thanks for all the replies guys. Would serve the spouse right to have cold showers. As it is, I wait until he is done with all his showering and shaving before I go anywhere near the bathroom. We currently have a 30 gallon tank and we never run out of hotwater.
Question: Can the mod/con be on the 1st floor and the indirect tank in the 3rd floor bathroom? Or will there be a lot of heat lost from the pipe runs? I was thinking that might be a workable solution.
I also do like the SuperStor Ultra which has a 20 gallon 27" h x 19" dia. shiny tank. Now, that I think about it, there may be a nearby closet into which I can fit it.