Need advice on new project

Tom_35

We are looking at a job that changes nearly every week. Today we met with the owners for 2.5 hours and following is what we came away with.

The lady wants her large shower heated to the point where she could go into it during the winter time to just sit in an area that is extremely warm. She would not be running the shower during this timeframe, but would have other times when she would be taking extremely long showers. The plumber will be installing shower heads from the ceiling and multiple heads on the walls. The shower is 6' x 8' long and will have 2 benchs.

We can get the walls and benches (with plates) and the floor will be in a lightweight pour with tile.

That is all the radiant they are planning on, even though they have a huge area in the his/her bathrooms and another bathroom downstairs at the indoor therapy pool.

They have a real power availability problem for the home and the 600 amp service is maxed out. We are adding 3 HVAC systems, a dehumidifier for the indoor pool, and they are having an elevator---which makes up the majority of the added electrical load. I have suggested the possibility of using a small boiler to heat the pool in lieu of the 12KW electric heater that is attached to the pool. We could use heat exchangers for the pool, the small amount of radiant, and the domestic hot water. They originally had planned on having an instaneous water heater like the Takagi, but would not be able to have a circulating domestic system with the instaneous unit.

This seems like a good method and would solve the power problem. Am I missing something?

Thanks,

Tom A.

Mike T., Swampeast MO

Modulating boiler serving the DHW and pool with a generously sized buffer tank for the shower radiant.

Mark Eatherton1

Or...

You could use one of the new Amtrol dual coil tanks, set a seperate HXer for the pool, and draw off the second coil on the tank for the radiant...

ME

jerry scharf_3

Take a look at the GFX waste heat recovery system

Tom,

sounds like a nutty customer "who is always right, both before and after they change their minds."

Rather than figuring out how to heat all the water for the "long showers", why not plumb a GFX unit into the waste stack for the shower. If it can recover 1/2 to 2/3 of the drain water energy, keeping up becomes much simpler.

The effectiveness of heating the pool has a great deal to do with the relative locations of the boiler and pool. If they are near by, then it can be a big win both cost and power budget wise. If they are far apart, the heat loss in the pipes can kill you.

Recirc is a current fashion for wasting energy. God forbid that someone would have to wait 20 seconds or more for hot water. If they want to save water, use a Taco d'mand unit.

jerry

Constantin

Now, now, jerry...

We wouldn't want to criticize a system I installed into my own home, now would we? :-)

But seriously, recirculation has its place. While installing electric on-demand units is a possibility in many homes, a victorian doesn't have the room. Plus, if you put the pipes into walls and surroud them with 2-4" of Icynene, I'd like to think that the water will stay warm for a good long time. Lastly, the recirculation system can be programmed to only come on during certain hours of the day, i.e. the morning and the evening.

However, I agree that a GFX system is quite interesting in terms of its capabilities. In our home, our waste stack doesn't become sufficiently bundled until the last drop before the sewage leaves the house. The added piping, low flow shower heads, etc. then discouraged me from installing the system in a mere one-family home. I can see why hotels, laundromats, and other high-volume users of water would love it though.

I also wonder how one can max out a 600A breaker panel. That must be a huge all-electric house... I would also consider solar panels to heat the DWH and/or the pool. In the winter, the pool circ is left off and the solar just heats the DHW, while in the summertime the pool is the prime beneficiary of excess solar gain.

hr

I'd suggest a modulating boiler with an Ergomax type reverse DHW tank. This would give you plenty of DHW and act as a nice buffer to a large boiler when only that small shower zone calls. I'd use a slab sensor type control for the shower enclosure.

I'm trying an outdoor pool currently with 3/4" pex in the floor! The pool is built with ICF's like the home. With a good cover it should be a pretty good heat sink. For a pool anyways

This way I eliminate any HXers as the boiler water circs through the 3/4" pex.

It's the owners idea, he already had the pex in. Worth a shot for the cost of the pex.

hot rod

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Tom_35

Constantin,

My finger hit the wrong number when I was posting this thread last night. The home is pretty large, but the service is 400 amp, not the 600 that I typed.

The pool requires a 105 amp circuit, which takes care of the heaters, and 4 pumps.

Thanks guys for the recomendations. I really appreciate the help and knowledge that comes from The Wall.

Tom A

Larry Weingarten

Without sounding critical...

...might I suggest having a closer look at the D'mand unit? (www.gothotwater.com)It is capable of giving very good service with a far smaller energy penalty than recirc with timer and/or thermostat.~~ Also, the GFX can be plumbed in to preheat a water heater, or simpler, just to heat the cold side of the shower. That keeps the related piping/heat loss small. In Very General terms, a $300 GFX can save about the same energy that a $2500-3000 solar DHW system can... with no upkeep.

Yours, Larry

Constantin

Very good points!

The D'Mand unit does everything our recirculation system does, except differently. The idea behind a D'Mand unit is that you have a long string of fixtures, at the end of which you hook up a D'mand unit that feeds warm water back to the cold side until it gets hot, right?

Well, my house may not be the model for all homes in America, but we have 3 different runs of piping distributing water in the place. Thus, we'd need three D'Mand units to keep the water up to temp. Conversely, with the walls open and the piping being replaced anyway, we have three ½" copper pipes coming back into the basement that go into a 003 Taco that is controlled by the Vitotronic.

Which system is cheaper to install? Undoubtedly, a D'Mand system is more economical once a house is built. Conversely, I can buy a lot of piping, installation, etc. for the $1,000+ installation that the 3 D'Mand units would cost me.

One aspect of the D'Mand system I do like is the ability to tie its activation to a room sensor or somesuch. That is very nifty. On the other hand, with the Vitotronic capable of excercising the pump on a set schedule, I think I can anticipate most times when demand for hot water is high and program it appropriately.

As for the GFX, it's a great investment if your vertical sanitation stack is anywhere near the plumbing. I also agree that I should have thought of preheating shower water with the drains. On the other hand, in our house the vertical sanitation stacks tend to be far away from the shower plumbing, so it would have required a lot of extra plumbing.

I did toy with the idea of using one GFX for the whole house... The 79" tall unit would probably do the trick (4"-in, 4" out, 1" pipe) nicely. However, the location of the last vertical sanitation stack in the house is at the other end of the basement from where the water heater is. Thus, I'd have to run something like 150' of 1" pipe to preheat cold water going into my indirect water tank.

With that much pipe to and from the GFX (and the requirement until recently to only use copper in MA for potable water systems) I didn't think I would see much benefit from pre-heating the water. Now that PEX is allowable, I may revisit the issue. We have some chases we could route the stuff through and a small manifold could then allow us to bypass the sanitation stack, if necessary.

Tom_35

This job is going south---

Received a call from the GC on this job and he said that the plumber went to a class on the Rinnai instantenous water heaters and they are going to provide a 199,000 btu heater for the home addition. One heater will take care of the 2 bathrooms and they are planning on having another 199,000 take care of the "very small" endless swimming pool.

They want me to provide a hot water heater for the radiant heating of the shower.

This is such a waste. I told the GC that the 199,000 heater is huge overkill, but he is convinced that it is the way to go. The plumber knows plumbing, but isn't well-versed in any kind of hydronics (we've followed behind him before and replaced circulating pumps where he has installed them in a "shaft down" installation; he can't figure out why he continues to lose pumps);

My guess is that he isn't planning on providing a heat exchanger for the pool heating and will hook the heater up direct to the pool.

Should I say something about the proper way to make this installation and how we could add a buffer tank and heat exchanger to their domestic system for our radiant heat, or should I just keep my mouth shut? I don't want this to sound like sour grapes to them since the boiler has now been deleted.

Tom A

S Ebels

\"Going South\"

This job looks like it probably will. I'd give a business card to the homeowner and the GC and tell them to call you back when the plumbers "system" goes South. It sounds like a nice future changeout/update job in the works to me.

You can lead a horse to water but.............