superstore problem

Dan C._4

I just put in a 80 gallon superstore in a group home. i bought from somewhere different than where I normally do and I had them size it for me. There are 5 full baths with 3gpm shower heads, One residential tyoe kitchen with a residential dw, one hand sink, and one bar sink. The customer needs to run 5 showers all at once and when he does that they run cold after 7 minutes. The boiler is 190000 output. The circ is a taco 0010. I seems like it is undersized but when I look at the chart the first hour rating is 330. So I figured at 15 gpm it should run for 22 minutes before it goes cold. That is not the case so I am assuming that I am doing it wrong. What would I have to do to satisfy his hot water demand? The guy is not very happy with me and I really need to do whatever it takes to make it right. Also I tried operating the superstore at 180 and mixing it down to 125 and it lasted 10 min. The existing set up was a 40 gallon gas rheem direct fired water heater and a 75 gallon state piped in series.

ed m

ss

what size pipe do you have feeding and returning from boiler?
what else is the boiler used for? priority?

Home Depot Employee

Not quite

In simple terms that rating is based on a hot start boiler at 180 degrees delivering 140 degree water that is mixed otherwise add 12-18 minutes to recovery calcs on a cold start boiler (common first heating in the morning). Actually 330 gallon 1st hour rating is only 5.5 GPM max draw over 60 minutes. Factor in that you wish to lower the tank temp to reduce scalding and your first hour performance is much worse.
Not knowing what the BTU ratings were of your prior tanks we know for sure you lost storage to the tune of 35+ gallons when giving some room for the seperate stratification of each tank. That 35+ gallons is the 2.5-3 minutes more per shower.

What your tank needs to be sized for is total storage required commonly known as dump load.

You will most likely need a bigger tank or the best solution is to install a second 80 gallon indirect or a storage tank with DHW circ.

Unknown

Control.

What type of control are you using to maintain temp. in the SS? What is the delta-T you are using before the pump comes on. Tighten it up it might help.

What size pipe, how many fittings and how far form the boiler? Is the boiler cold start? What is the supply and return temp from the SS coil?

Lot of things could effect the outcome.

Unknown

What model?

Wich do you have, the SSU-80DW or SSU-80C? My bet is the SSU 80DW. Either way the pump size is on the fence. Try a 0011.

Dan C._4

1\"

1" pipe from boiler and it is set for priority

Dan C._4

the old setup was 115000 btu total.

tim smith

math on 80 gals superstore

The way I see it, you have appx 60 gals of useable stored hot water, with 240 GPH of recovery. That equates to 60+ 4gpm of hot water. So in 7 minutes that is 88 gallons of available hot water. In 7 minutes the 5 3gpm heads at appx 70% full hot would be 2.1 gpm of hot x 5 x 7. Which is appx 74 gallons of hot water used in 7 minutes. That basically say's it is doing what it is suppose to. Good luck, Tim

Home Depot Employee

misconception

The biggest misconception is that an indirect can produce hot water near instantaneously. While some systems do better than others due to size/capacity of exchange systems, hot boiler starts, low mass boilers heating quicker, control systems, etc., it looks like your biggest issue here is lack of storage to meet the quick dump demand of all the showers functioning simultaneously.

Do you think for the sake of water conservation and perhaps saving your arse they will let you install restrictors in the shower heads to reduce flow? That .5 GPM less per head may save your but. Also if not already, you may need to set up that boiler on maintaining a low fire set point temp and priority if shared with heating anything else.

bobbyg_2

from everyone else's input I feel comfortable saying the storage is doing what it should.

To improve the situation, I would increase the pipe size to minimum 1-1/4" for easier 18 gpm flow (which will recover faster). Right now the 1" has a max. recommended flow of 8 gpm, after that, when you try to "force" the flow through faster - extremely more energy is required.

It won't help your tank storage, but it will decrease recovery time. Also what type of aquastat are you using? Is it a fixed differential or adjustable differential? If you can tighten that up to a smaller differential, that will also help.

Dan C._4

hd employee

I told him that he had to change the shower heads. So did the guy from superstore, the wholesaler that sized it for me, and also another guy that is trying to sell be a turbomax setup. The whole problem is that i misled him and made him think that he would have more than enough hot water not thinking that he would need 15 gpm of hot water. It is in his best interest to change the shower heads but by doing that he feels like I gave him something that is not as good as what he had. He says he had endless hot water before which is not true because the reason we did this was because he was running out of hot water. I never even thought to change the shower heads which I now realized are new and probably caused the whole problem to begin with. The whole thing is really my fault which is why I need to correct it. Thanks for all the help

Home Depot Employee

Fine

I'm sure your 1” piping size is fine assuming the boiler and tank are within close proximity. Someone may make the mistake and tell you that the pipe is too small but keep in mind those published flow rate ratings are typically based on 100’ of pipe. It wouldn’t surprise me one bit you are moving the net output of the boiler with the circ you have selected.

Check your delta t along with boiler temp rise and if the burner is cycling or not during a tstat call will confirm.

Think of it along the same lines of Primary/Secondary setups. The short piping distance injecting the heat to the system allows the pipe sizes to be smaller due to reduced friction.

tim smith

Regarding resolution

Maybe you should offer for goodwill, to change shower heads to low flow heads if calcs work out for this, gratis. That may be an easy way out to maintain a customer in good standing. Tim

adambuild

!

What temp is the tank storing water at? If not alraedy, why not boost it up to 140 or 150 and install a mixing valve?What te

scrook_2

330 first hour...

"but when I look at the chart the first hour rating is 330"

For what it's worth: that's at 212,000 BTU/hr boiler output, you said your boiler's 190,000 output, about 10% less.

More important they say the coil's 9.1 ft head at 12 GPM, but an 0010 can only do about 8.5 ft at 12 GPM, so even without any extra tubing to/from the boiler you're running at less then 12 GPM, maybe 10 GPM or so if the tank's fairly close to the boiler?

An 0012 circulator might do a lot better than the 0010 if you're shooting for 15 GPM.

bobbyg_4

No matter the piping length, when you try to get 18 gpm out of a 1" pipe I don't like the velocity and friction loss/ft. If it is copper, erosion could be an issue later. (I don't have my B&G system syzer here at home to see exactly what the velocity would be)

Home Depot Employee - would you say 1" pipe would be ok for around 18 gpm?

Dan C._4

already tried that

he gained and extra 3 minutes

Dan C._4

Tim

I have no problem doing that. That is what I want to do. That is the whole problem is the shower heads. The customer feels he shouldn't have to change the shower heads because he thinks he had enough hot water from the old system which is not the case. He started having problems when the new shower heads were installed

SpeyFitter

You are correct Bobby and it's not what I would do either but, the system is in the money is collected and the man has a problem. Changing only the pipe at this stage won't save him.

Suggesting to change the pipe would only dig his hole deeper at this point, he is short on storage.

Joe Mattiello

sizing a pump correctly

I agree the 0010 does not have enough capacity for that application. Attached is a technical document Taco published to help you methodically size a circulator correctly.

Dan C._4

thanks

Thanks everyone for all the help. I think I am going to put a 0011 or 0013 on it and hopefully that will do it. He changed the shower heads but hasn't gotten back to me yet on the results. I guess worst case I'll have to put in another 80 gallon storage tank. In the future I will be very careful about what I promise people and I will never rely on a wholesaler to size anythingfor me again. Thanks again.

Home Depot Employee

Excellent, but-

"I will never rely on a wholesaler to size anything for me again."

Keep the faith man, there are some good wholesale employees out there that know what their doing! As always you must think it through yourself and decide if their selection makes sense. Also, the good ones typically don't compete on price but can offer a solution at a competetive price.

(Note: I don't work for HD, in fact don't work at all, just picked screen name for fun and effects)

[Deleted User]

picked screen name for fun and effects?

which can affect the perception of your credibility, despite the appearance of your knowledge

Home Depot Employee

Mike
I've never in my life been concerned about other peoples perception of me, why start now?
I'm always here to answer your wood and paint questions
LOL

[Deleted User]

ah, the flip-side of jfk

where reality is more important than the perception?