Building a new home - 1 tank or 2?

[riverside67]

I am in the process of designing a custom 3632 sq ft home that will have 2.5 baths.
- powder bath = sink and toilet
- Bath #2 = shower, rain shower head, toilet and sink
- Master bath = 110 gal roman tub, two sinks, toilet and large shower with rain shower head, two wall heads and 1 set body sprays.

I am currently specing 1-50 gal water heater that will serve the powder room, the kitchen, the laundry room and bar sink.

The 2nd heater will be an 80 gallon that will only serve the master bath and bath #2.

I am wondering if two tank heaters are really necessary? We have configured it this way since the house is 132 ft long and the master bdrm is at one end and the laundry, kitchen and powder at the other. We wanted to make sure we had a hot water source capable of filling the tub and/or not have to wait for 8 minutes before hot water got to our master bath shower.

Does this configuration make sense?
Would it be better to have 1 large tank heater to serve the entire home instead?
Maybe something larger than 80 gallon?
What about some kind of recirculating system to expedite getting hot water to the furthest parts of the home?

I appreciate any help that can be offered!

[SewerRatz]

I have always found Bradford White's sizing guild to be helpful. http://rightspec.bradfordwhite.com/Sizing/Residential.aspx The plumber installing the system can properly size and install a recirculation system.

[SewerRatz]

Also AO Smith has a great piping diagram on how to install two tanks with a return line. http://www.hotwater.com/lit/wiring/315268-000.pdf

[jadnashua]

You can't get the full volume out of a tank, so, depending on the relative temperature of your cold in the winter and how hot you keep the tank, you may have trouble filling that big tub, especially in the winter unless you go bigger. Using a tankless (gasp) would likely require at least a couple in series to get the flow rate to keep the time to fill that tub to a reasonable interval...you wouldn't want it to cool off by the time it was full! You'll also want 3/4" lines and valves, otherwise it will take 20-30 minutes to fill the tub.

I'm not sure either is a good choice...see what the others think. When you get to really large tanks, you end up in the commercial range, and some of those are designed to output huge amounts of hot water that would be fine for the whole house at whatever flow rate you'd normally use.

If the heater is a ways from the furthest point, you'll want to have dedicated return lines so you can do recirculation, especially critical if the lines are 3/4". Make sure to insulate them well. If you lay them out properly, you may be able to keep the lines hot without a pump, although using a pump on a timer or occupancy switch might save a little, if you can wait. It definately will save water, and it is really nice having hot available without running the tap for awhile.

[Scuba_Dave]

I have a single 50g electric feeding 2.5 baths
But my ~3000 sq ft house is only maybe 50' from end to end for water delivery. So only 14' in one direction & 36' the other - plus 16' to the 2nd floor
We have a hot tub outside, so we don't fill up the inside tub that often.
Plus the inside jacuzzi tub has a heater built in

Bradford sizing says 80g for me
But the 50g works fine

[gusherb94]

Our house has three bathrooms with six bedrooms and the master bath has a 100 gallon whirlpool and a shower which is all being served by a 50 gallon high recovery heater for the past 19 years and it's been getting along ok that way with the consideration that no one can shower while the tub gets filled. when the heater gets replaced it will be with a 75 gallon tank. for your place i would suggest maybe one 100 gallon tank the two tanks sounds good too but it would cost more to operate two instead of one or maybe bradford white's high performance water heater.
http://www.bradfordwhite.com/products2.asp?id=1&product_id=168

Jonathan

[jimbo]

I would take advantage of the spec. service available from Bradford White and Rheem.

Even assuming that you will only put actual about 75 gallons into the tub, and 80 gallon tank in normal set up will only give you about 56 gallons of water hot enough for a bath. What you might want to do is get a high BTU unit, and also install a tempering valve, so you can set the heater up to a higher temp, around 160º. This will give you a larger volume of water hot enough for the bath.

Given the length of the house, having heaters in two locations makes a lot of sense. If you don't do that, then a recirculating system makes sense.

Although some of us have not drunk the "tankless coolaid" yet, you are an application where that could also make sense. But do a lot of homework. Many people tend to underestimate the size of tankless required, which is a fatal error. You also have to factor in annual maintenance cost into your equations. You MUST do annual ( perhaps twice a year in hard water!) service, or you will kill it.

[riverside67]

Gusher:
Thanks for the link! The BW 55 gal HP tank costs ~$1500. Would this be a better investment than two normall 50 gals in series?

Where can I find a 100 gal tank?


Jimbo:
The water in our area is known to be quite hard. This may rule out tankless unless we install a softener (which we likely will be doing).

I was hoping to have one 80 gal tank more centrally located for the home but the design doesn't allow that. I mean what's a few more minutes of water running besides the wasting water part right? Of course that means more $$$ down the drain...

[hj]

The size and number of tanks is less important than where they are located. If you can position one tank near one center of use and the other one at the other end of the house, two tanks make sense. If they are both located at the same point then there is no advantage, other than storage capacity and recovery rates, for multiple tanks.

[gusherb94]

[QUOTE=riverside67;192390]Gusher:
Thanks for the link! The BW 55 gal HP tank costs ~$1500. Would this be a better investment than two normall 50 gals in series?
efficiency and recovery wise i would say so.
Where can I find a 100 gal tank?


I would assume your local supply house would have one if not then i dont know.

[kingsotall]

Also AO Smith has a great piping diagram on how to install two tanks with a return line. http://www.hotwater.com/lit/wiring/315268-000.pdf

Is that considered parallel or series¿ What is the difference as far as why one would be piped in any two ways¿

[riverside67]

That looks to me like it's parallel as both tanks are recieving cold inlet water at the same time. Series would be if one got the cold first and then the outlet of the first went into the inlet of the 2nd. Correct?

Would running two tanks in series even make a difference in thier performance and/or is this even recommended by the manufactures?

[riverside67]

for your place i would suggest maybe one 100 gallon tank the two tanks sounds good too but it would cost more to operate two instead of one or maybe bradford white's high performance water heater.
http://www.bradfordwhite.com/products2.asp?id=1&product_id=168
Jonathan

We will be using LPG as our fuel where we are building. Can any "gas" tank heater be converted to LPG? I cannot find anything on the BW website that states specs about the GX-1-55S6BN being able to be ran on propane.

[SewerRatz]

Is that considered parallel or series¿ What is the difference as far as why one would be piped in any two ways¿

That is a parallel set up which does require the piping from the tee to each heater to be exactly the same, meaning same amount of valves, same amount of fittings, and same exact length of pipe. Lets now say they both are 50 gallon units, now you have 100 gallons of hot water to draw off of.

Now if you pipe them in series, where the first heater is cooking the water then the outlet of that heater feeds the second tank then the outlet of the second tank feeds the building. So here the school of thought is you are preheating the water to the second tank which will help make them recover faster.

http://i7.photobucket.com/albums/y292/SewerRatz/Plumbing%20pics/serieswaterheaters.jpg

So basically you get more hot water in parallel, and faster recovery in series.

[SewerRatz]

We will be using LPG as our fuel where we are building. Can any "gas" tank heater be converted to LPG? I cannot find anything on the BW website that states specs about the GX-1-55S6BN being able to be ran on propane.

When you order the unit from the plumbing supply just tell them its for LP gas Here is the link to the LP unit http://www.bradfordwhite.com/products2.asp?id=25&product_id=179

I have installed a few of the GX-2-25 already, everyone of my customers loves the unit. They are able to fill their 80 Gallon soaker tub and there was water left over to shower or wash dishes. The unit also recovers really fast as well.

[jimbo]

We will be using LPG as our fuel where we are building. Can any "gas" tank heater be converted to LPG? I cannot find anything on the BW website that states specs about the GX-1-55S6BN being able to be ran on propane.


NO. Water heaters cannot be converted from nat. to LP. You must buy a purpose-built LP model.

[gusherb94]

When you order the unit from the plumbing supply just tell them its for LP gas Here is the link to the LP unit http://www.bradfordwhite.com/products2.asp?id=25&product_id=179

I have installed a few of the GX-2-25 already, everyone of my customers loves the unit. They are able to fill their 80 Gallon soaker tub and there was water left over to shower or wash dishes. The unit also recovers really fast as well.

Would you say that water heater is enough to serve a building with two apts each with one bath one washer and dishwasher and a store with a sink for light dishwashing use?

[SewerRatz]

Would you say that water heater is enough to serve a building with two apts each with one bath one washer and dishwasher and a store with a sink for light dishwashing use?

I have seen the GX-2-55 handle a two flat with no complaints. Granted the lay out is pretty much what you said less the store with a sink. Worse case scenario is you install it and it can not keep up you can always add a storage tank with a recirculation pump and an aquastat to give you a bit more of a buffer.

[riverside67]

I would prefer not having a recirc system and the reason I need to decide is that the 2nd water heater is taking up valuable space in our floor plan. If I do not really "need" that 2nd heater then that space can be re-captured into the home. Plus it would mean somewhat less piping, etc (i.e. ..cost)

[SewerRatz]

The recirculation system I was talking about is for the storage tank. IF the storage tank water temp goes down the pump would turn on and start heating the water. Have a look at this piping diagram.http://www.hotwater.com/lit/piping/A0380.pdf I do service work at a restraint that has this exact set up with the vertical tank of 180 gallons, that Burkay boiler can turn that 180 gallons of ice cold water into 180° F in 15 minutes.

Now what I was saying is you put the GX-2-55 in the place of the boiler and install a 50 gallon storage tank, you should have endless amount of water.

[riverside67]

Now what I was saying is you put the GX-2-55 in the place of the boiler and install a 50 gallon storage tank, you should have endless amount of water.

Hmmm...interesting idea. I will have to think about that one for a while.

I don't think I ever stated this info before. The mstr bath and bath #2 in the home are both about 75 feet from the tank heater in our garage. If we install a 2nd, as it's currently designed, then those distances become 20 and 30 feet, respectively.

[riverside67]

Anyone have any input regarding the distances of the water heaters to the master bathroom and if 75 feet is too far for typical uses?

[riverside67]

We are finalizing our building plans and I really need to decide which way to go for our hot water needs.

Should I go with two different tank heaters in the two different locations or should I use one heater and one storage tank in the garage to serve the entire home (knowing the master and bath #2 are 80 feet from where the heaters would be in the garage)?

Thanks

[jadnashua]

Assuming your supply line is 3/4", there's about 7 gallons of water in the pipe from the WH to the furthest location (shortest distance which may not be valid). Unless you use recirculation, you'll throw away about that much water in the pipes that has cooled off to get hot, and take about a minute or so to do it (at a tub), probably longer, especially on a sink or shower which can only flow maybe 2.2gpm.

So, unless you can put the tank closer to the point of use, or do something else to mitigate that, you'll probably not be happy without recirculation or a small tank in the bathroom to take up the slack before it arrives from the main source.

[riverside67]

So what if I was to install two - 25 gallon high performance Bradford White GX255S6BN water heaters in the garage (plumbed in either series or parallel, whichever is better) with a recirculating system?

Supposedly these 25 gallon heaters can provide 155 gals (each) of hot water in the first hour. This would mean an available 300+ gals of hot water with a recirculating system.

The only thing...how do recirculating systems work and are they subject to problems?

My supply lines from the heaters to the master and bath #2 will be 1" minimum.

[jadnashua]

A single tank would likely have lower standby losses. not familiar with that tank, so don't know the details.

There are all sorts of recirculation systems. If you can provide a dedicated return line, it works best, but using the cold works with some compromises. Lots of discussions here on this subject, use the search function. If there's any way to place a heater closer to the point of use, you could likely eliminate the recirculation. Cost to use it isn't huge if you insulate the lines and can live with it on a timer so it doesn't run when you are unlikely to need it.

[riverside67]

Considering this is new construction the recirculation line should be simple to add to the plan.

Is having two tanks in series a big waste of money? My wife and I love long hot showers and will have a soaking 100 gal tub. I really think we need this much hot water avaiable.

Do recirculation pumps need to be sized based on certain criteria?

[riverside67]

After doing some research last night I am leaning towards using the Grundfos UP10-16 recirc pump with a dedicated hot water return line.

Now the only thing I need to decide is what type, and how many, water heaters I'll need in the garage. I'm still thinking at least one BW high performance GX1-55S6 or GX2-25S6 and/or possibly two of the 25 gal units in series with the first one set at a lower temp so as to not waste too much propane but to keep the water warm basically to pre-heat for the 2nd tank.

We have decided to eliminate the water heater in the master WIC for a coulple reasons, distance from water softener (which will also be in the garage), possible noise from the unit coming into our mstr bdrm, and most of all loss of valuable space in our WIC (that is very important to the wife FYI).

Also, since we will be using a private well and septic system it makes sense to utilize a recirc system to eliminate unecessary pump runs and cold water going down the drain and into the septic tank on a daily basis while we wait for hot water to get to the point of deliveries.

Please let me know what you all think of this scenario.

Thanks for all your input.

[hj]

IF the parallel installation works "perfectly" and few do after a couple of years, then you get the SAME amount of water from either a parallel or series installation, and since you have two burners with either one, the recovery is the same also. With a parallel system, the two heaters MAY fail at the same time, but not likely, however, unless the new heater is exactly the same as the old one, you lose the "mirror image" requirement of a parallel installation, so you almost have to replace both heaters anyway. With a series installation, which is the only way I have ever installed two heaters, the first one will outlast two or more second ones and there is no possibility of "short circuiting" the flow, and the two heaters can be different makes, models, or sizes.

[riverside67]

Ok, so maybe it would be better that I connect two tanks in series.

Would an "in series" design basically be where the hot water from tank #1 feeds the cold water inlet to tank #2 and the the hot water out from tank #2 feeds into the home?

If I went with this setup how would a dedicated hot water return line be plumbed into this setup?

Thanks