[HeatherJ]

Hi there,
Here is our dilemma:
New home as of 8/1/10....Tankless boiler that heats our water to a 40 gallon Amtrol tank, 3 bathrooms, two people living here that each shower usually 2 times each daily.

We recently had family stay over a weekend and one person took a hot shower and then two hours later two other people took showers and they started to get cold right away. We also notice that we have to turn the showers way up to get a nice hot shower going.

We've had the guy back out several times on other minor issues with this but the troubleshooting step he is suggested is that we have hard water and the water heater is corroding due to this and thus, we've not getting hot water to the showers. So.....we've had Kinetico and Culligan both out to test the water and we're at 6gpg which is hard water but both guys said that there is no way that in 7 months, it could corrode the water heater.

Unknowing to us, we didn't realize we had only a 40 gallon tank (long story-->we requested a tankless water heater and assumed the tank hanging on the wall was that, but it actually is a tankless boiler...yeah, we're still fighting the builder on this one) Anyway, to us, 40 gallons seems to be too small for our needs.

Here's the question: is the system set up incorrectly or is it the inadequate size of the water heater? With the Amtrol system, the next size up is 80 gallons and while that is fine and dandy, what if he switches that out and it's actually the system? I'm sorry I don't know other details, but does anyone have any ideas on this?

Thanks for your help!
Heather J in MN

 

[yuri]

Does this boiler heat radiators and the house also? There are lots of different tankless wall mount water heaters/boilers and they are rated in BTU's (amount and rate of heat they can produce at a certain gpm/gallons per minute flow rate which in laymans terms is the recovery rate or how fast it can produce hot water and how much). Yours may be too small/undersized. You need an experienced plumber who sells lots of them for a living to see what size you need. Also need to factor in that the water coming out of the ground in your area is a LOT colder than in Florida so you need a bigger heater. If it is a dual boiler/water heater setup then it needs a proper recirculating line from the tank to the boiler and recirculating pump and controls setup properly and mixing valve etc. Post a pic of the boiler and storage tank and model number and brand of boiler.

 

[AllanJ]

Can you show us a picture of your system?

When you have a hot water tank that is heated by a furnace coil instead of a built in gas burner or electric elements then the furnace needs a separate zone for the water tank versus the house radiators.

The coil must be forced with a circulator pump. The tankful of water won't heat up quickly if the coil flow relies on incoming water pressure and occurs only when someone takes a shower or otherwise uses hot water or the coil flow relies on temperature gradients (gravity flow).

 

[HeatherJ]

As I understand it, the tankless boiler on the wall heats the water for the water heater for our home and also heats the radiant tubing for our in floor heat. We do not have a furnace in our home (we love the infloor heat!).

We both shower daily if not twice daily and either do laundry every day or every other day, as well as the dishwasher every day or every other day. In doing my math, a 40 gallon tank seems too small but here is what our GC emailed back to me in regards to it being the correct size for our 3 bathroom home:
"The capacity of a water heating device is determined by how quickly it can produce hot water, not the size of its tank. If you review the specifications for your Amtrol unit, when combined with your boiler it can produce up to 143 gallons of water per hour at a 90 degree rise at boiler output of 80,000 but."

If we had guests and we all used the showers which are 1.5gpm low flow showers, in 10 minutes all the hot water would be gone in the water heater. And when the GC spoke of 143 gallons heated within an hour at 90 degrees, well 90 is not warm enough and if we had to wait an hour to get that much more, it seems like we're not even close. I know I'm not a plumber, but things just aren't adding up for me.

In speaking with our contractor that put in the system (he is trying very hard to get it corrected for us), he said he'd like to get a 80 gallon tank in there for us. So, since we found out that our hard water is just basic hard water (6 grains) and that there is no way it could have corroded the water heater in this 7 month time, we know that is not the issue. We worry that if he gets us a bigger water heater, how do we know the system is working correctly. There are a lot of what ifs and questions going on, we're not sure where to proceed. He doesn't want to switch out the 40 gallon we have at present (even tho to me that seems like the first troubleshooting step), but I understand the labor involved. But the GC thinks that is should be fine.....

Ugh!!! I'm sorry, I'm kind of rambling with this post. I've attached a picture so you can see the set up. If you need more info I can get that too. We have a Triangle Tube boiler and the water heater is an Amtrol tank.
Thanks guys for your help so far. This has been a long 7 months of craziness with this general contractor.......

 

[bob22]

" at a 90 degree rise" should mean if incoming water is 50 degrees, the water will be heated 90 degrees more to 140 degrees in one hour.
Go to:
http://www.google.com/url?sa=t&sour...sg=AFQjCNHkl5bQGcCGFoA0or2hVuN5ve27Zw&cad=rja
for more detailed explanations of heating water, rates, etc...

 

[AllanJ]

The heater is supposed to heat the incoming water at the same time as you are taking a shower or otherwise using hot water. So if you don't draw it too fast and you wait 15 minutes between showers then you shuould not run out of hot water.

It is not unusual to find a 40 gallon stand alone gas water heater in a 3 bedroom house.

There should be a thermostat inside the water tank (you should see the wire coming out) and this turns a circulator pump on to send boiler water around in a loop between the wall hanging boiler and the water tank.

 

[beenthere]

As above, its 90 warmer/hotter then the incoming water temp.

Next, an 80,000 BTU output boiler can not recover 143 gallons an hour at a 90° temp rise. Amtrol's with an 80,000 BTU output boiler, are rated at 139 gallons continuous at a 70° rise. Not very hot if your incoming water temp is less then 55°.


Post the full model number of both your indirect and the boiler.

Good chance its a poorly set up system.

 

[HeatherJ]

Thanks Bob22--Finally, someone takes the time to explain what the plumbing jargon means! GCs and subs would get hired more if they took two minutes to do this.....

Here's the specs on our set up:

Triangle Tube Prestige Solo 100 Water Boiler
Amtrol Boilermate Indirect-Fired Water Heater Classic Series--Dial Aquastate, Double-wall Heat exchanger--41 gallons

 

[beenthere]

The 110 should be able to heat your domestic water ok. Can you post pics of the piping.

 

[HeatherJ]

Here are some pics of the piping. Sorry, not sure why they upload sideways

 

[secutanudu]

My neck hurts!!!

 

[bob22]

I don't think it is any easier to follow right side up vs sideways. A lot going on there!

 

[beenthere]

Don't think I saw a purge valve for the indirect. If there isn't one, then air could be trapped in the indirects coil, and reducing its recovery ability.