Hot water runs out after indirect empties
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What controls can you see under the cover/door of the boiler? Pictures please.
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The indirect will give you a buffer of hot water, but if the boiler is too small to heat the water at the rate you are consuming it, which is very likely if your winter incoming water temp is somewhere in the 30's or 40's, you will eventually run out. You need to store enough energy in the tank to last throughout the demand, but no matter what it won't be unlimited.Denniss516 said:However it might be that some thing from the very beginning is the issue. Without the storage tank of course we didn’t have enough hot water at that point the storage tank gives us more but it runs out.
I might have missed it, but what size is that boiler?
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Yes, multimeter !! I saw that on youtube to measure across the two screws, it didn't make sense to me. I thought that circuit was a series circuit, a simple open and closed circuit. Ohms would blow my meter with voltage there, so I didn't do that. That was my first troubleshooting thought. Ok, so I can do that VAC???? I just checked aquastat should arrive Thursday, I now feel that was a waste to order. I always prefer troubleshooting first !!mattmia2 said:Do you have a multimeter? That would be where I would start. You should measure 24vac across the aquastat when it is off(open) and 0 vac when it is on(closed).
Flex-flexible metalic conduit or in that case it might be metallic cable, but in any case, it is the line voltage wiring that goes to the circulators.0 -
It is a series circuit. If the aquastat in the series is closed then both terminals are the same point in the circuit and you should read no voltage difference across it. If the auqastat is open and all the other devices in series are closed, the voltage from the transformer with be present on each terminal through those devices but since there is no current flowing in the circuit so there is not voltage drop over the other devices in the circuit, you will see the voltage of the transformer across where the series circuit is open.0
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I try it tomorrow thanksmattmia2 said:It is a series circuit. If the aquastat in the series is closed then both terminals are the same point in the circuit and you should read no voltage difference across it. If the auqastat is open and all the other devices in series are closed, the voltage from the transformer with be present on each terminal through those devices but since there is no current flowing in the circuit so there is not voltage drop over the other devices in the circuit, you will see the voltage of the transformer across where the series circuit is open.
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Replaced Aquastat today, I did read 24vac across it. Waiting for wife to take those showers again to monitor. Thanks, dennisDenniss516 said:
Yes, multimeter !! I saw that on youtube to measure across the two screws, it didn't make sense to me. I thought that circuit was a series circuit, a simple open and closed circuit. Ohms would blow my meter with voltage there, so I didn't do that. That was my first troubleshooting thought. Ok, so I can do that VAC???? I just checked aquastat should arrive Thursday, I now feel that was a waste to order. I always prefer troubleshooting first !!mattmia2 said:Do you have a multimeter? That would be where I would start. You should measure 24vac across the aquastat when it is off(open) and 0 vac when it is on(closed).
Flex-flexible metallic conduit or in that case it might be metallic cable, but in any case, it is the line voltage wiring that goes to the circulators.
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What I found very interesting today for the first time, my hand is on the output to DHW to the left that pipe I assumed was an input from cold. Today after about 30 minutes after my wife said the water got cold, that pipe was hot !!! Obviously, I am not a plumber and have no idea what I am talking about but that pipe to the left was always cold. Does this mean anything? Does anyone live in NY? Long Island?0
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The lower tapping should be the inlet and the upper tapping should be the outlet so that it draws the hot water off of the top of the tank. If it is plumbed backwards, hot water capacity will be reduced because it worn't be able to take advantage of stagnation in the tank to remove more of the hot water before it begins mixing with the cold incoming water, but If I am understanding what you are saying, your hand is on the outlet which is what it should be.
It likely will still be hot but not as hot as the draw continues for an extended period. The boiler is still heating a lot of water, it just can't add enough energy to bring it up to the storage temperature of the tank instantaneously.0 -
Can you follow the pipe that you had your hand on?
Does it go back to the water meter?.....if so that is the cold water supply.
And then one would conclude that it is piped backwards.
You would have only maybe the lower 1/4 of the tank for storage.0 -
I took a video to maybe explain the system I have easier.
https://youtube.com/watch?v=pLdZM01jjJE0 -
The water supply to the boiler comes in to the fitting that the expansion tank is attached to. The boiler itself is a sealed system, it recirculates the same water, water only enters through that valve if there is a leak or if water is release through a drain or bleeder valve. There is a coil inside the indirect water heater that boiler water circulates in and heats the water in the tank. The 1 inch pipes are the boiler water that circulates in the coil to heat the tank.
It isn't unusual for hot water to migrate out of the indirect tank through convection and make both the inlet and the outlet pipes hot. If the pipe that is connected to the tapping near the top further left is cold and the pipe that is connected to the tapping at the bottom is hot while there is a big draw like with someone in the shower or the hot water at a tub or laundry sink open, then it is plumbed backward. Run the hot water in the tub or the laundry sink and feel both those pipes on the left that connect above each other at the top and bottom of the tank and let us know which one is hot and which one is cold. A couple clear pictures of where both those pipes connect to the rest of the plumbing up near the ceiling would also help. I see that there is a big green valve on one but I can't see where the other one connects.
The hum from the circulators when they are off might be from the control transformer in the boiler resonating up through the piping.0 -
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i think that the inlet and the outlet of the domestic water side of the water heater are correct. i was concerned that they were reserved, but it sounds like they are correct in this video. The cold water inlet pipe will get warm when there is no hot water demand because some hot water will rise out of the tank by convection.
The 2 1" pipes connected near the bottom of the tank are connected to a coil in the tank. The top one should be the supply and the bottom is the return. The circulator pumps water out of the boiler in to the coil in the tank then the bottom pipe joins with the other returns and brings the return water back to the boiler to be reheated. Those other pipes you are tracing around are the returns to the boiler from other zones.
If both those pipes are very hot and you still aren't getting enough hot water than either the tank is too small for your winter incoming water temp or the coil is scaled up or possibly a little of both. you could gain a little more capacity by raising the setpoint on the aquastat on the tank and adding a thermostatic mixing valve to the output of the tank to bring the temperature of the water down to a safe level.
Here is a cutaway of that tank:
https://www.htproducts.com/images/SSU-Inside.jpg0 -
You only talk about the shower. Do you lose hot water at all other fixtures? Maybe it's not a "hot water" storage issue but an actual plumbing issue.
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Pick a time when there has not been a call for hot water for a bit and all 4 pipes are close to room temp.
Here is what normal operation should be:
Shower turns on, 3/4" pipe going to bottom of tank gets colder, 3/4" pipe from top of tank gets hotter. At no point should the lower 3/4" pipe get hot.
Within a couple minutes, the boiler is triggered and the 1" pipes start getting hot, probably too hot to touch. The top pipe should be 10 to 20 degrees hotter than the lower pipe. The boiler should fire soon after as the boiler temp drops.
Does your system do this?"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
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Yes all faucets supply cool water from the hot faucet once the 45 gal are used up, my problem is at that point the boiler shows 170 degrees. Why doesn't the boiler supply hot water into the Indirect as the 45 gal empties? I hear water movement, yet it takes maybe 20 minutes for the temp of the DHW to return. When the heat goes on, almost immediately the boiler goes on.Hilly said:You only talk about the shower. Do you lose hot water at all other fixtures? Maybe it's not a "hot water" storage issue but an actual plumbing issue.
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what tells the boiler to refill the indirect with hot water? It seems cold water is refilling the indirect. After 20 minutes DHW is hot again, why so long? I believe the Aquastat in the indirect is for high temp shut off. we don't have hard water here, I was told scale can't be my problem. When I spoke with HTP that is what he thought my issue is.mattmia2 said:i think that the inlet and the outlet of the domestic water side of the water heater are correct. i was concerned that they were reserved, but it sounds like they are correct in this video. The cold water inlet pipe will get warm when there is no hot water demand because some hot water will rise out of the tank by convection.
The 2 1" pipes connected near the bottom of the tank are connected to a coil in the tank. The top one should be the supply and the bottom is the return. The circulator pumps water out of the boiler in to the coil in the tank then the bottom pipe joins with the other returns and brings the return water back to the boiler to be reheated. Those other pipes you are tracing around are the returns to the boiler from other zones.
If both those pipes are very hot and you still aren't getting enough hot water than either the tank is too small for your winter incoming water temp or the coil is scaled up or possibly a little of both. you could gain a little more capacity by raising the setpoint on the aquastat on the tank and adding a thermostatic mixing valve to the output of the tank to bring the temperature of the water down to a safe level.
Here is a cutaway of that tank:
https://www.htproducts.com/images/SSU-Inside.jpg0 -
I was told, by the oil burner installer years ago and the plumber that installed the gas boiler from oil, I should never run out of hot water, yet after a 15 minute shower, hot water runs out0
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I don't recall if this has been recommended:
Turn the house heating tstats down so there is no call for heating.
Then close all the valves that are in the house heating piping.
Keep open only the valves that are in the 1" water heater piping, insure that water can travel out of the top of the boiler, thru the WH pump, into the tank and out again and then return to the lower part of the boiler.
The boiler water comes out of the top to the pump manifold, gets pumped to and returns to the lower left pipe into the bottom of the boiler.
Doing all of the above, should allow only the WH tank (coil) to heat.
Keep all your domestic water supply valves open, that is the hot and cold to tub, sinks etc.
Run hot water down the tub and see how long it lasts.
The boiler and the WH pump should run for a long time.
The house heating piping should not get hot more than a few feet from the pumps or return connection.
It is possible that you are sending hot boiler water thru the heating zones as you are trying to make hot water.
Remember, the boiler does not "fill" the tank it just sends hot boiler water thru the coil (that you can't see) inside the tank, this coil being hot then heats the tank water.
The tank fills with cold water and pushes hot out of the top to the tub etc.
The two liquid never touch.
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If the 2-1" pipes are very hot with very little temp difference and the boiler does not fire constantly as the tank temp drops, your coil is scaled up.Zman said:Pick a time when there has not been a call for hot water for a bit and all 4 pipes are close to room temp.
Here is what normal operation should be:
Shower turns on, 3/4" pipe going to bottom of tank gets colder, 3/4" pipe from top of tank gets hotter. At no point should the lower 3/4" pipe get hot.
Within a couple minutes, the boiler is triggered and the 1" pipes start getting hot, probably too hot to touch. The top pipe should be 10 to 20 degrees hotter than the lower pipe. The boiler should fire soon after as the boiler temp drops.
Does your system do this?
You are making this more complicated than it is. The 3/4" cold pipe replaces the water that leaves the tank out the 3/4" hot pipe. The 1" pipe just circulates water through the heat exchanger coils when the aquastat tells it to. The boiler fires when the boiler water goes below it's setpoint.
When the coils are scaled, the heat transfer happens at a very slow rate and your spouse runs out of hot water and gets mad at you.
Replace the indirect and the problem will be solved. I would look for a model that does not have all those little fins for the scale to build up on.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein1 -
I will do this, thanksJUGHNE said:I don't recall if this has been recommended:
Turn the house heating tstats down so there is no call for heating.
Then close all the valves that are in the house heating piping.
Keep open only the valves that are in the 1" water heater piping, insure that water can travel out of the top of the boiler, thru the WH pump, into the tank and out again and then return to the lower part of the boiler.
The boiler water comes out of the top to the pump manifold, gets pumped to and returns to the lower left pipe into the bottom of the boiler.
Doing all of the above, should allow only the WH tank (coil) to heat.
Keep all your domestic water supply valves open, that is the hot and cold to tub, sinks etc.
Run hot water down the tub and see how long it lasts.
The boiler and the WH pump should run for a long time.
The house heating piping should not get hot more than a few feet from the pumps or return connection.
It is possible that you are sending hot boiler water thru the heating zones as you are trying to make hot water.
Remember, the boiler does not "fill" the tank it just sends hot boiler water thru the coil (that you can't see) inside the tank, this coil being hot then heats the tank water.
The tank fills with cold water and pushes hot out of the top to the tub etc.
The two liquid never touch.0 -
Denniss516 said:
I looked at the cutaway, maybe a stupid question. 45 gal of hot water in tank. How does the DHW leave the tank? Is there a pump for that? Does the call for DHW get the pressure from the cold water coming in and when the tank is full the water has to release and go somewhere? Does the tank know when the water in the tank gets cold? Or, The coil 1" gets cold and the burner senses it and turns on to reheat that coil? Because those 1" pipes are very hot and burner at 170 when no DHW.mattmia2 said:i think that the inlet and the outlet of the domestic water side of the water heater are correct. i was concerned that they were reserved, but it sounds like they are correct in this video. The cold water inlet pipe will get warm when there is no hot water demand because some hot water will rise out of the tank by convection.
The 2 1" pipes connected near the bottom of the tank are connected to a coil in the tank. The top one should be the supply and the bottom is the return. The circulator pumps water out of the boiler in to the coil in the tank then the bottom pipe joins with the other returns and brings the return water back to the boiler to be reheated. Those other pipes you are tracing around are the returns to the boiler from other zones.
If both those pipes are very hot and you still aren't getting enough hot water than either the tank is too small for your winter incoming water temp or the coil is scaled up or possibly a little of both. you could gain a little more capacity by raising the setpoint on the aquastat on the tank and adding a thermostatic mixing valve to the output of the tank to bring the temperature of the water down to a safe level.
Here is a cutaway of that tank:
https://www.htproducts.com/images/SSU-Inside.jpg0 -
How hard is your water supply. The indirect has an aquastat on the tank to tell the boiler to start up. Your DHW has no pump. Your boiler side will have a pump and or a zone valve.0
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Water here is not hard at all. Lived here all my life. I was amazed traveling up state NY the soap was difficult to remove from my body during a shower. Here on Long Island, the soap comes off very easily. I thought this Aquastat is what you said, but it said in the instructions it is high limit. That might not be important as I set it the lowest it goes, 130. My confusion is when we call for DHW what moves the water out? Is the tank full of hot water and when we call for DHW, new water goes in with the water co. pressure? The 1' coils in and out are very hot during DHW use. So, I feel that is good. I feel the problem is the new water isnt either filling up the tank or a sensor is not asking for more water. Or, cold water is mixing with the DHW somehow, I need to isolate the heating system and see what happensbucksnort said:How hard is your water supply. The indirect has an aquastat on the tank to tell the boiler to start up. Your DHW has no pump. Your boiler side will have a pump and or a zone valve.
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For example: if you had a garden hose outside with a pistol grip control on the end and the wall faucet turned on to the hose. When you squeeze the pistol handle, water will come out......what pushes that out? Your house plumbing water pressure does!
The same thing for your hot water, the tank is connected to house water pressure, (should be at the bottom) when you open the shower valve (think of the hose pistol handle) the cold water pushes the water thru the tank (at the top) and out the pipe to the shower.
Now your house pressure is probably 60 PSI of pressure, if somehow that water could get into the boiler coil inside the tank, then the boiler would get pressurized up to 60 PSI. The boiler should operate under 30 PSI. If it goes over 30 the relief valve will open and water will come out onto the floor....you will notice this happening.
Yes, your hot and cold domestic water could have a cross connection and you get cold mixed into the hot. But you would notice this in many places. For instance warm water flushing the toilets or watering the lawn.
The most common source of this is a faucet that has the hot and cold both turned on and the spout is shut off be some means. Mop and laundry sinks are the first suspects. Or a shower valve that has a 100% shut off on the shower head. This is why your tub spout or shower hose should dribble when in use if you try to shut them completely off.
Did you try the isolation of the heating system yet??0 -
No I have not yet as I need to be home when my wife is showering. I was trying to understand the indirect, so now I get it. It is just that a tank like a full can of beer except there is a coil on the bottom heating up the beer. seems simple enough, when the beer cools because cold (i'll switch to water) water enters the coils heat up to heat the water. so then why does the burner stay at 170 and the coils are very hot? Why doesn't the coils in the tank cool down with the cold water entering?JUGHNE said:For example: if you had a garden hose outside with a pistol grip control on the end and the wall faucet turned on to the hose. When you squeeze the pistol handle, water will come out......what pushes that out? Your house plumbing water pressure does!
The same thing for your hot water, the tank is connected to house water pressure, (should be at the bottom) when you open the shower valve (think of the hose pistol handle) the cold water pushes the water thru the tank (at the top) and out the pipe to the shower.
Now your house pressure is probably 60 PSI of pressure, if somehow that water could get into the boiler coil inside the tank, then the boiler would get pressurized up to 60 PSI. The boiler should operate under 30 PSI. If it goes over 30 the relief valve will open and water will come out onto the floor....you will notice this happening.
Yes, your hot and cold domestic water could have a cross connection and you get cold mixed into the hot. But you would notice this in many places. For instance warm water flushing the toilets or watering the lawn.
The most common source of this is a faucet that has the hot and cold both turned on and the spout is shut off be some means. Mop and laundry sinks are the first suspects. Or a shower valve that has a 100% shut off on the shower head. This is why your tub spout or shower hose should dribble when in use if you try to shut them completely off.
Did you try the isolation of the heating system yet??0 -
Scaling on the coils is insulating them from the domestic water and reducing heat transfer. The supply and return being hot and similar in temp along with the boiler temp not dropping is the telltale."If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
I agree, it makes the most sense. When I spoke to HTP they said the same thing !! So I looked into it. However, this issue has been going on for many, many years. The HTP was replaced under warranty five years ago, the problem still existed as well as I was told by two different plumbers that is not my issue because we do not have hard water here. We have lived with this forever, we thought this was normal to run out of hot water after showering for 15 minutes (normal showering time) Since the pandemic, we put this on the front burner to try to resolve realizing that we should not run out and we were told by the installers we should have plenty of hot water.Zman said:Scaling on the coils is insulating them from the domestic water and reducing heat transfer. The supply and return being hot and similar in temp along with the boiler temp not dropping is the telltale.
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Did it do this ever since it was installed, maybe only in the winter?
You could just be using more hot water than that coil can make. if the incoming water temp is say 35 degrees it is only going to make maybe 1.5-2 gpm of 90-100 degree water. if you have a shower head that consumes 3 or 4 or 5 gpm that is just far more heat than the coil can transfer to the water no matter how big the boiler is. if the boiler is fairly large it may be able to heat the water much faster than the coil can transfer to the tank which would mean it wouldn't fire all that much. Looking at the rating plate, the boiler is about 100,000 btu/hr. That should match the coil in the tank pretty well, but it won't be able to make more than 1-2 gpm of hot water once you empty the tank if the incoming water is cold.
The fist thing to do would be to set the shower head how you would if you were using it and time how ling it takes to fill a bucket to say 3 gallons. if you are only using say 1.5 gpm then there is some other issue like the pump is moving water so quickly through the boiler it never mixes properly or someone is running the hot water out of the spout at full flow for a couple minutes before changing to the shower head.0 -
Humor me, if I missed it in all the posts. What is the cold water supply pressure coming into the house from the street??? 55psi would be excellent.
Close up pic are nice, but medium range pics from many angles are easier to diagnosis.
I especially like the pics that I can do a close up with the computer cursor and move around.0 -
Is there priority for indirect,
Is the 1"" piping FULL size ? Or is it supposed to be 1 1/4" ???
Is well probe corroded ?
Put circ on hi speed ,
Flush tank and coil after above if needed.0 -
Can you drain the tank and send an borescope in through the hot or cold fitting?
It would be an inexpensive way to verify..."If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
Appreciate everyone's help with this issue. This issue does seem to be more of a problem in winter, assuming we take hotter showers in winter. I believe water pressure is normal as it does seem to have plenty of pressure, outside hose, faucets etc. When I slightly turn the 1/4 shut off valve I hear the water slowing down, I first thought little water in, little water out. I replaced the aquastat 2 weeks ago. How to raise the circulator speed? To repeat my original issue, DHW 45 gal empties in about 15 minutes, burner does not turn on because temp is 170. 1" pipes in and out of storage tank are extremely hot. I hear water movement. I believe DHW is hot again after about 15 minutes.0
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Tank was replaced under warranty 5 years ago, issue was there before and after tank replacement.Zman said:Can you drain the tank and send an borescope in through the hot or cold fitting?
It would be an inexpensive way to verify...0 -
what is the flow of the shower head and does someone run the tub a while before switching to the shower head?0
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Can you measure the 1" supply and return temps?
Measuring the flow of the shower would be a good idea. You can time how long it takes to fill a bucket or time the water meter with only the shower running"If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
mattmia2 also suggested the same thing: demand outstripping supply.Zman said:How many gpm is the shower pulling?
You have a very high flow shower head and the system simply can't keep up.
I have experience with this at my old farm in Vermont. I plumbed one of my showers with 3/4" copper from my 50 gallon indirect (which was supplied by 1" pipe from a deep well capable of delivering a LOT of water) and drilled the shower head out to be more of a power washing experience than a shower. This was to deal with hard days getting covered with hay, hydraulic oil, and tractor grease. A good cleaning and a deep tissue massage at the same time. The only problem was this setup would empty the indirect and go to lukewarm water in about eight minutes. So much for the "unlimited" water supply from an indirect plus larger boiler.
I think that's what's happening here. Try using a bucket and a timer to measure your shower head flow. My bet is it's over the usual 2.5 GPM and this is why your setup can't keep up.
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https://www.youtube.com/watch?v=XUJBNNHid7k
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