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Not enough hot water--need help!

Hi--thanks in advance to all who can help me.
Background: I am married with three girls. They take showers that are usually longer (wash hair!). Typically 2 showers run in my house at same time. We also have dishwasher, laundry, etc. But usually dont run together.
I have a lennox boiler with 113k btu output (140k btu input).
I had a separate gas hot water heater (GE 75 gallons). It turned 14 years old recently, and instead of it waiting to break, I decided to replace.
Doing some research, and hearing from some friends, I investigated installing an indirect hot water heater system. All the #s I saw showed that the output of the indirect would be greater than a gas hot water heater.
So I bit the bullet, had my boiler rewired with a priority switch, repiped to the new Heat-Flo 60 gallon I purchased. It included a mixing valve as well.
The mixing valve is set at 115 degrees F.
The Heat-Flo is set at the maximum 160 degrees F.
I had all plumbing and electric double checked.
The problem: when 2 showers are running, within 20 minutes, we run out of hot water! When I had my gas hot water heater this did not happen! I had the heat-flo inspected by the company to confirm there is nothing wrong with it. The only thing they could tell me is that even though my boiler is rated to put out 113k btus, its 13 years old and could be putting out less.
I am really upset. My family is so frustrated that we spent so much to switch over and yet we now have less hot water than we had previously with a seperate gas hot water heater. I am throwing my arms up at this point and giving up. My only last option is to rip out everything I did and go back to a seperate high-output gas hot water heater.
Hoping maybe the experts here could possibly come up with something to solve my issue!
THANK YOU!
Background: I am married with three girls. They take showers that are usually longer (wash hair!). Typically 2 showers run in my house at same time. We also have dishwasher, laundry, etc. But usually dont run together.
I have a lennox boiler with 113k btu output (140k btu input).
I had a separate gas hot water heater (GE 75 gallons). It turned 14 years old recently, and instead of it waiting to break, I decided to replace.
Doing some research, and hearing from some friends, I investigated installing an indirect hot water heater system. All the #s I saw showed that the output of the indirect would be greater than a gas hot water heater.
So I bit the bullet, had my boiler rewired with a priority switch, repiped to the new Heat-Flo 60 gallon I purchased. It included a mixing valve as well.
The mixing valve is set at 115 degrees F.
The Heat-Flo is set at the maximum 160 degrees F.
I had all plumbing and electric double checked.
The problem: when 2 showers are running, within 20 minutes, we run out of hot water! When I had my gas hot water heater this did not happen! I had the heat-flo inspected by the company to confirm there is nothing wrong with it. The only thing they could tell me is that even though my boiler is rated to put out 113k btus, its 13 years old and could be putting out less.
I am really upset. My family is so frustrated that we spent so much to switch over and yet we now have less hot water than we had previously with a seperate gas hot water heater. I am throwing my arms up at this point and giving up. My only last option is to rip out everything I did and go back to a seperate high-output gas hot water heater.
Hoping maybe the experts here could possibly come up with something to solve my issue!
THANK YOU!
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Comments
When the hot water priory takes over: The boiler has to run up to a higher temp, (mine goes up to 180), It takes a good sized pump to move the boiler thru the tank heat exchanger.....more than you might use for house heating perhaps.
Also all the water goes to the tank HXC, might use a heat flow check to keep the water directed to the HXC and not sneaking off into the house heating system.
There may be a differential adjustment for the tank temp.....making it fire early before tank cools off too much.
Bob
Vaporstat with a 12oz cut-out and 4oz cut-in
3PSI gauge
Now with the indirect, we need about 40 gallons of makeup water; 2 gpm. So we need a minimum of 60,000 BTUh to handle the flow.
So the question is -- is the indirect actually putting that much heat into the water? It might be worth measuring the supply and return water temperatures from your boiler, and the flow, to see...
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
And as much as I would like to limit shower time, when the girls have friends over there is usually 2 showers going one after another!
System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
Brewbeer--I had both the plumber and the heatflo company check the circulator that pumps the return to the boiler to ensure its the correct one for my unit, Its a variable speed circulator. And yes they said it was correct. its set on the fastest speed which is what everyone recommended.
The boiler goes between 170-180. As the boiler drops to 170 it turns on till reaching 180 again.
My thought is there is not just 1 thing that is the problem but a number of small things that are leading to this. 75 gallons is still 15 gallons more that you have now.
you have less dump with the smaller tank it seems that is the difference, assuming all is working correctly
is the indirect coil piped properly
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Hard to tell from the angles given in the photos, but if you don't have a check valve in the DHW boiler circuit, you need one. Otherwise, when the space heating pump is on, fluid will be short circuiting through the DHW tank, losing that stored energy.
I'd check temperature differentials on the boiler supply and return lines to the DHW tank, under load (running two shower heads at full flow) and near the end of the cycle. If working correctly, you should have a bigger delta T when under load than when it is nearly satisfying the tank set point. Check it where it leaves the boiler and returns back to the boiler, as well as where it goes into and comes out of the boiler side of the tank.
You've got a slipping clutch somewhere...
ME
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
At 140F domestic we have 2.95GPM. But this is based on a 14 GPM flow rate from the boiler through the coil. The chart also reads this is based on a boiler output equal to at least 132,340 BTUH. You state yours is 113,000 BTUH. There isn't enough boiler output to meet the specs. So even if the tank is at max temp, and at this point I would want it on standby at 160F, with a mixing valve set at 120F you might just approach a satisfactory situation provided 3 GPM is not exceeded and you might just get the storage capacity equal to a 78 Gallon tank. All bets off if we exceed 3 gpm after drawing off the first 80 Gallons.
I know this because this is what I do and I also have 3 daughters.
I know a boiler has to be at 90% afue and have a min. 150,000 BTUH INPUT to maintain 3GPM to the shower head; but that is the limit. Any more draw than 3gpm will not keep up.
When we see and do the engineering we can work the solutions.
Your boiler heating needs are set for radiation temps? If this is below 180F you will have to reset this. Go up to 200F is the next option. If the boiler temp does not drop than the flow rate between tank and boiler is probably not 14 GPM. This is much higher than a normal heat zone which is usually 3-5GPM. Did the installer measure the flow rate, record and provide you the performance data? PS. All mfg ratings are based on 50F inlet cold water. In Maryland we spec for 40F cold water for winter. It makes a difference. In yesterdays world the building heat loads exceeded domestic hot water loads and the boiler was large enough. Today with smaller building heat loads the domestic hot water load is the greater. You would not believe how many jobs I see that lack the engineering, proper application and correct installation required to make it right. I have job security for many lifetimes ahead. my chart ref: https://www.heat-flo.com/pdfs/Indirect Water Heaters - Spec Sheet.pdf
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
If he needed more fire it seems the boiler would not cycle but slowly fall down in temp while constantly firing. FWIW
I have a 3200 sq' house with 3 baths, two of which is mostly used. I have a HTP Munchkin 140 M boiler and at my altitude, I have a 12% derating of the boiler output. So, I have about 123K BTU output.
My boiler is connected to a 45 gal HTP indirect water tank. I never run out of hot water, ever. The boiler has a DHW priority over space heating. The boiler fires at 185 deg for the DWH and on Out Door Reset for space heating. The water storage in the tank is set at 150 deg with thermostatic mixing valve regulating the supply temp to the house at 120 deg. The tank is set by the boiler at a 5 deg differential. The cupro-nickel heat exchanger in the tank is 1".
kunisk, your system and some ideas.
What is the water temperature supplied by the boiler to your indirect tank?
Does your boiler give priority to the indirect when it calls for heat?
What is the indirect's Heat Exchanger size and the material it is made of?
What is the make and model of the pump supplying the boiler water to the indirect and is the pump only supplying boiler water to the indirect and nothing else?
Why set the thermostatic mixing valve set to 115 deg instead of 120 or 125 deg?
What I think is based on those questions. Your boiler must be giving priority to the indirect when the indirect calls for heat over space heating. The aquastat on the tank must have a small differential and not 15 deg. It may be adjustable, set it for a tight differential. The pump must be capable of delivering the BTU's to the HX in the indirect. The flow thu the HX, and consequently the transfer of the BTU's from the boiler water to the tank water, is dependent upon several factors. The pumping power, the HX tube size and design, and the temperature of the boiler water.
What I think may be happening to you to cause your problem is--
The boiler water is too low a temperature and not a priority setup. The HX in the indirect is too small, so that the flow thru the HX is too slow, therefore, not transferring enough BTU's. The indirect pump is not powerful enough to increase the flow thru the HX. Your tank differential is too wide and set to a low a tank temp.
I like a hot DHW temperature, just because it kills Legionnaires' disease bacteria.
Personally, I don't think you have the flow thru the HX and that is certainly what I would want to know, first.
I built my own HXC from a scrap of 3' x 8" pipe from the farm iron pile. Put in 20' of 3/4" copper for a bundle. Initially with 100,000 input I would not run out of hot water with a house full.
I changed boilers and from trial & error and just using the pumps available, I now have a smaller pump for the bundle and my recovery is much less. But with a 120 gallon tank and only 2 people we get along.
It sounds like the boiler is having no problem keeping up. But is all of its power going to the storage tank.
Do both of your pumps now have check valves in them? Or are there any in the system?
A picture from farther away would help, we can zoom in on our side of the computer.
Here are some answers to some of the questions....
--The circulator is a Taco 0015 MSF-IFC circulator with three speeds. Its set to the fastest one. The circulator only supplies to the hot water heater.
--Hot water heater (Heat-flo 60) is set to 160 degrees. The mixing valve is set to 115 degrees.
--Boiler does fire quickly after falling below 180 degrees at about 170 degrees. To me that means the hot water heater is getting hot water from the boiler. The aquastat is a honeywell and i replaced it already to confirm it is working properly.
--I am not sure how the "air" gets out of hot water heater, although my plumber did say he bled the system for any air pockets and their is a check valve.
--Indirect hot water heater is installed correctly. I had two other plumbers look at it.
--Dip tube is welded on to unit per Heat-flo so unlikely an issue.
--The hot water heater is on priority on the boiler.
-Plumber said doesnt want to push boiler to 200, could cause issues in other areas.
--Pipe size is 1" plumber said main is 3/4" so not going to have flow with higher pipe size.
***One thing that Lance mentioned. Heat-Flo chart says I need 132k output. I only have 113k. That is on me. I thought with 140k btu coming loss would be a small amount, not 20k. I mentioned this to my plumber and he said he strongly does not think its an issue as the water coming from boiler is extremely hot, any hotter is not going to help. He believes that for some reason the hot water flowing through the indirect is just not heating up the water fast enough (he doesnt love heat-flo, thinks its garbage but put it on based on my request). My last step is going to be putting a thermometer on the boiler return and supply to hot water heater so I can see the differential. This will help tell us if the heat-flo is doing its job.
A HUGE THANK YOU TO EVERYONE FOR TRYING TO HELP! Keep the advice coming and any creative ideas on how I can get more hot water I am all ears as is my plumber (who is a friend of mine).
Also attached is another pic.
This seems to be part of the problem, 3/4" pipe can't deliver the full load of the boiler that the indirect can accept.
System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
Looking at the DHW piping next to it.
1" to the top of the pump?
1 1/4" below the pump?
Just checking my senior eyes.
Your "supply to the heat source" and your "hot outlet" are mixed up." The thermostatic mixing valve hot input is connected to where the boiler supply is suppose to be connected. There is no reason that the boiler supply to the tank and the boiler return
from the tank have to go to the ceiling.
Sounds like you are definitely not getting enough flow to even make your boiler pull down very much. You might even want to take the pump apart to make sure it isn't restricted. No offense, but there is a lot of solder and pipe dope floating around there, and it might have got in to the pump.
Rick
The delta t (temperature difference) between the supply and return temp is a big clue. As Mark noted, if there is no check valve on the heating circ, that could be the problem.
You will be surprised how much information can be a attained by simply feeling the pipes.
If everything has been thoroughly checked, for the normal issues, it is time to start looking for the weird stuff.
Clock the gas meter, check for junk the factory or plumber left in the pipes....
This system should outperform the old one. You just have to figure out what is wrong.
Albert Einstein
I do believe you are onto the problem with the use of 3/4" and the cycling of the boiler when making DHW.
Take a look at the last photo. If my old eyes do not deceive me, the supply is the iron pipe at the rear of the boiler. Follow it up and it changes to copper after the air separator.
Then, you can barely make out a set of what appears to be 1" x 1" x 3/4" tees. If one of the 3/4" lines feeds the indirect, that would pinpoint the problem.
Need better photos of the piping between the boiler and the indirect.