Not getting much hot water

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  #1  
Old 03-17-13, 09:09 AM
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Not getting much hot water

My Boiler (PB) is about 6 years old. It is an oil fired boiler. Its on demand hot water (no boilermate). Sence new we have had trouble with our hot water in our sinks, and shower. The installer came back a few times and changed the mixing valve twice. We tried a couple other service companys and they did the same.

If I turn on hot water at a faucet, and go check boiler, the hot pipe comming out of furnace is only warm. The temp is set for a high limit around 170 i think. After about 55 minutes the water gets hot, but it cools down within a few minutes.

What would cause this?

Thanks,
LimeChild

aka E. Child
 
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Old 03-17-13, 09:16 AM
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whats the lo and diff set at?
 
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Old 03-17-13, 09:20 AM
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not sure. Im at work right now. Just thought I ask a few questions. I will check when I get home. Thx
 
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Old 03-17-13, 09:29 AM
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If you set for a higher diff it will hold the circ off longer for when there is also a call for heat. Lo should be a min of 20f below the hi setting.

Of course the coil can be scaled up too. Whats your water quality?


 
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Old 03-17-13, 09:32 AM
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I will check it out. For some reason it seems to be worse in the winter.
 
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Old 03-17-13, 09:50 AM
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I believe the water quality is good. Im on town water. They say its drinkable...
 
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Old 03-17-13, 09:54 AM
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Even city water can be on the 'hard' side though, meaning high in calcium and magnesium. Those are the minerals in the water that can 'scale up' a tankless coil. Not harmful to drink, perfectly safe, but can be a problem in other ways...
 
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Old 03-17-13, 09:54 AM
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If I take a picture of the inside of the control box, would that help?
 
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Old 03-17-13, 09:55 AM
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picture of the inside of the control box, would that help?
As long as we can see the dials and pointers, yes!
 
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Old 03-17-13, 09:58 AM
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great. will try to do it when I get home later this evening.
 
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Old 03-17-13, 03:18 PM
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Here you go.....Let me know what you think. Thanks guys
 
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Last edited by limechild; 03-17-13 at 03:25 PM. Reason: no picture
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Old 03-17-13, 05:00 PM
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There's a shadow on the DIFF control so I am not sure where the pointer is...

If it's all the way down on 10, bump it up to 20 and see how that goes.
 
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Old 03-17-13, 06:00 PM
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its on 15. i will try 20.
 
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Old 03-18-13, 07:49 AM
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5 min not 55. sorry for the typo
 
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Old 03-18-13, 07:56 AM
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I set the diff to 20 and it didn't make much differnce.
I would think that when I turn on my kitchen hot water faucet that it would be hot within a few seconds? Then I would need to add some cold.


After I set the diff to 20, I turned on hot faucet, and ran down to the furnace. It took atleast 5 minutes for the furnace to turn on. After 10 minutes, the water comming out was still not very hot.


Could the gray box I took a picture of be bad?

Thanks again,
 
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Old 03-18-13, 08:03 AM
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What does the temp on the boiler read when you run the hot water? What mixing valve do you have and whats it set for? They stick sometimes. I know its new but turn the dial a few times back and forth...

Take some pics.

Yes the aquastat can be bad but we need the temps.
 
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Old 03-18-13, 10:21 AM
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I will take a few pics with hot water running and furnace on.

I will take a pic of the mixing valve, but the pipe leading to it isnt that hot. I will use a temp gun and shoot it while its calling for hot water.
 
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Old 03-18-13, 11:16 AM
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pictures

Here are pics of the gauges.
Temp was 180ish when I turned on faucet.

After 8 minutes it was 160ish and boiler just turned on.

after 20 minutes with boiler running for 12 minutes I could still hold onto the pipe from boiler to mix valve.

Mixing valve is on hottest setting.

Once I turned water faucet off and then turned back on 5 minutes later, the water was too hot to hold hand under. It lasted for about 1 minute then only about 100 degrees.

Hmmmmm
 
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Old 03-18-13, 11:57 AM
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So with a high setting of only 170f the boiler makes 190f water? Looks like a newer gauge, but it could be off... I doubt it though.

Additionally the aquastat could be fault or the capillary is not seated in the well properly.

One more note is that mixing valve is of the cheap variety and is not an antiscald valve. I saw a few of those and where the handle stops at 160f there is a stop under the handle. As a test I often lift the handle and reposition it past the stop. this will get you another turn out of the handle.

Possibly the above will help. Is the mixer the issue? Could be.


This is the proper valve you should have.


http://s3.pexsupply.com/manuals/1249...00-6.0_REV.pdf


I would doubt its the coil since this was an issue since new, right. Take farther pics of the piping......
 
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Old 03-18-13, 01:16 PM
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Here are a few more pictures of the lines comming out of the boiler.

When the boiler is running, shouldn't the copper line comming out that goes to the mixing valve be too hot to hold onto the whole time its calling for hot water?
 
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Old 03-18-13, 01:56 PM
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Here are what the instructions say. Did they do the below?

IMPORTANT: BE SURE TO REMOVE THERMOSTATIC
ASSEMBLY from valve before sweating connections,
otherwise it will become damaged


Additionally you may have unequal pressures. Meaning cold flows better then through the coil. More cold is feeding the mixer then whats flowing through the coil. A balance valve should be added.

*A valve should be installed in cold water line to hot water extender tempering valve, as shown, to help compensate for pressure drop through heater.

Also says a 8-12" heat trap and check valve should be installed, but I believe thats for hot getting in the cold line...

Here are the instructions and troubleshooting.

http://media.wattswater.com/1910210.pdf


I am still concerned about the temp being off. 170f aquastat setting and 190f boiler temp... ??? Thats a big difference and will affect the lo/circ too......
 
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Old 03-18-13, 02:19 PM
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The boiler was installed spring of 04. In the winter of 08 a differnt tech guy put in a complete new mixing valve assembly. Yes he did all soldering without the guts in the valve.

It seems to me that the water comming out of the boiler isn't as hot as it should be? It should be too hot to hold on to while boiler is running? Correct?
 
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Old 03-18-13, 02:24 PM
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It seems to me that the water comming out of the boiler isn't as hot as it should be? It should be too hot to hold on to while boiler is running? Correct?


You mean the heating side or the hot water side???


You said this... You have always had this issue right?

Since new we have had trouble with our hot water in our sinks, and shower.
Let me ask you what tyrpe of shower valve do you have? Is it the thermostatic type? Meaning separate on/off and temp control?

Sorry it seems we are going in circles. Just trying to help diagnose correctly....







 
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Old 03-18-13, 02:40 PM
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on the boiler side. the pic with my fingers on it.
 
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Old 03-18-13, 02:49 PM
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OK the pic with your fingers on it.

1. You have always had this issue?
2. It could be a balance pressure issue. I posted the instructions so you can understand. Possibly not enough flow through the coil. Should have that valve installed or better yet a better mixer. If it was flow with the better mixer the valve would shut off basically.
3. Coil can be scaled up. But did you always have this issue?
4. What type of shower valve? If thermostatic that can be your issue. The shower valve can be letting cold in the hot line, hence low flow through the coil.
5. Aqustat temp does not mach temp gauge. This could affect circ on time during call for heat and hot water.... IMO should be addressed...

Lets see if we can get other advise.....


Trooper or anyone else have any suggestions?????
 
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Old 03-18-13, 02:56 PM
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Temp was 180ish when I turned on faucet.

After 8 minutes it was 160ish and boiler just turned on.

after 20 minutes with boiler running for 12 minutes I could still hold onto the pipe from boiler to mix valve.

Mixing valve is on hottest setting.
At the time you were doing this testing, had the heat just been on? Is that why the boiler was already at 180?

Why did the boiler turn on at 160? Again, was a thermostat calling for heat at the same time?

There's a few things to understand about the coils.

The MORE water you pump through it, the COOLER the output will be. The water flowing through the coil requires CONTACT TIME to transfer the heat to the coil.

This means that turning the mixing valve up hotter may be counter productive, and certainly counter intuitive!

If the coil is scaled up, this issue becomes worse.

You can easily test this if you want to.

Leave the mixing valve set on full hot.

Turn the tap on a TRICKLE and let it run. Hot pipe out of coil should be much hotter than when the tap is on full blast.

AT BEST, these types of coils are good for maybe 3 GPM. Any more than that and you get cool water.

More about the control in next post.
 
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Old 03-18-13, 03:04 PM
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after 20 minutes with boiler running for 12 minutes
Did the boiler temperature eventually recover to 180 after running for 12 minutes?

=============================

If you want to see if the control box (the aquastat) is operating properly, you need to turn all the thermostats in the home down so that they don't 'interfere' with the test.

With the settings that you have now ( 150 LO and 20 DIFF), and the thermostats turned down, the burner should fire when the boiler cools to 140. It should then continue to fire until the temperature reaches 160.

I asked you to increase the DIFF because this will cause the burner to fire LONGER.

When there is a HEAT CALL from the thermostat(s), the burner will fire until the water reaches the HIGH setpoint which is shown at 170 in your pic.

If you are seeing something different than this, your temp gauge or your aquastat, or BOTH could be a bit 'off', but this probably doesn't have anything to do with the hot water situation.

more...............
 
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Old 03-18-13, 03:12 PM
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I think that for starters, you are expecting too much from the worst way in the world to make domestic hot water... well, SECOND to worst, you could be boiling a kettle on a woodstove.

Again, AT BEST, consider 3 GPM the max flow through the coil in order to get hot water. Any more than that and the water will be cooler.

You may well have a scaled up coil, AND the mixing valve may be whacked.

1. Lower your expectations.

2. Replace the guts of the valve.

3. If all else fails, try to find someone to do an 'acid boil' of your coil and clean the scale out.

These points are presuming that your aquastat is functioning properly.

4. Abandon the coil, convert the boiler to 'cold start', and get a REAL water heater.

Was it you who mentioned that the hot water is WORSE in the winter? This is probably because the entering water is colder.
 
  #29  
Old 03-18-13, 04:10 PM
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I will try the drip test tomorrow if I get a chance.

My old boiler didn't have this trouble, it just broke alot.

I thought with a system like this we ought to be able to take a shower or do the dishes and have to add a little cold water from the faucet/shower.

Maybe its the mix valve although it seems to me that the water should be hotter comming out of the boiler into the mix valve.

Im a papermaker and do carpentry on the side to make a living. I dont know squat adout this kind of stuff....

Thanks for all the help
 
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Old 03-19-13, 08:30 AM
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I left my kitchen faucet run with just a trickle comming out for aboout 10 minutes. The water was to hot too hold hand under. The line comming out of boiler was too hot to touch as well.

To much too fast I guess.

Thanks for the help,
E Chiild
 
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