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Hot water starts hot but gets cold quickly.

23K views 31 replies 8 participants last post by  rosco 
#1 ·
Hello all. This is my first post here. Recently the hot water in our shower started getting cooler and cooler. When we start out we have to mix the hot water with cold to get a nice temp but during the shower we have to reduce the cold water until it is completely off and the water still gets cooler.

What we have in the house is an old Columbia Co. Boiler that heats our house using a 3 stage baseboard system and it also heats our tap water. Heating the house seems fine but for some reason recently the tap water has not been staying hot.

Looking at the gauge in it's idle state (not using any hot water for a while and the furnace not firing up recently), the gauge reads 10PSI and the temp is at 160.

Last season we had our pump go out and had to replace it but from what I see, that is a totally different system. It looks like the tap water goes into the boiler cold and comes out hot. Looks like only 2 pipes for that system where there are a lot of pipes going in and out and splitting for the baseboard heating system and the pump is connected to those pipes and not the tap water system.

Any help would be great. If you need more info to help answer this question let me know and I will try to respond as good as I can.
 
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#2 ·
Sounds like the tankless coil is insulated with mineral build up.

It can be replaced. Or cleaned out. But cleaning it out involves a acid that could eat through the copper of the tankless coil.

Now would be a good time to consider either getting an electric water heater. Or an indirect hooked up to your boiler.
 
#3 ·
Now would be a good time to consider either getting an electric water heater. Or an indirect hooked up to your boiler.
My dad has been saying that for a while. Kinda broke right now but sounds like a good idea for tax return. Any suggestions to get me by for a couple of months?

Thanks for the reply neighbor! I just added info to my bio so you probably didn't know but I am in Ephrata, just a few miles from Lancaster.
 
#5 ·
No I didn't know that.

Not really anything you can do. other then having the coil cleaned. And cross your fingers it doesn't harm the coil.
Plus. Cleaning a coil like that is a time consuming job, so it can be expensive.
 
#6 ·
This sounds alot like the problem i am having and and when i moved into my house back in october the local oil company came out and cleaned the furnace i wonder if this could have casued this ? also i have a service agreement with my local oil company i wonder if this service is covered for the cleaning of the coils? i also mentioned my problem to them afterwards and they told me that it was my faucet is there any way i can push this back on them to prove that it is in faact my faucet?
 
#7 ·
Go to your kitchen faucet. Run hot only(for how ever long it would last in your shower). if it runs out, then its not your shower. If it doesn' then its your shower.

Most service contracts don't cover cleaning the coil. Its often refered to as "cooking out the coil".
Since the action of the acid causes it to heat up. as it eats the mineral build up.
 
#8 · (Edited)
then it must be my shower, i get 10 + minutes of boiling water coming from my kitchen faucet and bath room faucet. But the odd thing is it seems to be a problem with both of my shower faucets.

to add another note this morning the water was hot for half as long as normal and wasn't nearly as hot as previous days. the temp has droped here alot to the teens thru the night thou not sure if that has an effect on it.
 
#10 ·
Yes, its possible.

Run the shower. Open your access panel. Keep touching(lightly) the hot water line. If it stays hot while the shower water gets cooler and cooler. then its the valve(o-ring or seal bleeding through).

If it gets cold. Then your shower uses a lot more hot water then your kitchen sink and vanity do. And thats why they stayed hot the whole time.
 
#12 ·
The pipes aren't cooper pipes they are color coded and seem pvc like but a little softer. the pipes must be insulated they are really hard to get a temp by feeling them, well at least the hot even as it is steaming coming out of the faucet isn’t heating the pipe enough to burn my hand. But i took out the balance valve and didn’t see anything but I attempted to blow air thru the valves and the one side passed air thru freely and the other side had a ton of resistance. Does that mean the balance valve could be bad? The balance valve had air resistance on the hot side so i put it in the opposite way to see if it made a difference but it didn’t. Should i go track down a local supplier of parts and attempt to replace that piece? i'd hate to put out 100 bucks for piece that wont resolve my issue.
 
#13 ·
When you ran your kitchen and bath faucets. Did you run them both at the same time.
if not, do so.
If you still have good hot water for 10 minutes like you were taking a shower(cheaper test then rebuilding a valve that isn't bad).
Then you probably need to rebuild your shower faucet.
 
#14 ·
just a thought if you read the warranty listed on the page you posted a link for it says lifetime warranty but it looks like its limited to leaks so call them and say both of your faucets are leaking and they will provide you with new cartriges. you may also try posting this in plumbing section if you havent already
 
#16 ·
Just a couple of things to have a pro look at... before doing anything drastic.
When was the last time the boiler had service and the flues cleaned?
And by cleaned I mean thoroughly brushed with a properly sized wire flue brush and vacuumed out?
The reason I ask is because I’ve seen boiler flues so badly caked with soot and deposits that heat transfer was inadequate to keep up with demand with tankless domestic hot water.
You start out with a hot shower and it gradually gets cooler and cooler over about a 10-15 minute period, even though the boiler is still firing. Probably even more quickly if there happens to be a call for heat at the same time your using the domestic hot water.
A malfunctioning hot water extender [also called a mixing valve] at the boiler is another common problem that’s generally not too expensive of a repair.

 
#18 ·
i purchased the valves so i didnt have to wait at a local store. the boiler was just cleaned in Novenber after we moved in. this morning the water got alittle hotter compared to what it has been. But still after a few minutes the temp gets luke warm and will stay luke warm but if i back the handle down towards cold the tinest bit it gets cold almost as if there was no hotwater. But the sink has steaming hot water coming out of it while this is all going on so i think it my be isolated to the faucet. Not sure but it is starting to seem like the hot water presure for the shower is dieing down.. not sure what could be casuing that also the hot water pressure for the bathroom sink and kitchen sink are fine.
 
#19 ·
Do that same test again. With all faucets running(including the clothes washer. If after the same amount of time. You still have hot water. One of them is bleeding cold water into the hot water line.

Then just go back through and turn off one faucet at a time. Wait a few minutes and see if the water gets cold, if not then turn the next one off. When you turn one on, and a few minutes later the shower is cold. That one is bleeding through.

While the bathroom vanity and show should be feed by the same line. Thats not always the case.
 
#23 ·
i adjusted the cap so when i turn the handle all the way it should only be allowing hot water thru the faucet. Even then it seems like the water still isn't as hot as it should be compared to other faucets, but the hot water pressure seems low is there a possible adjustment for this on my boiler? And could this be the root of the problem?
 
#25 · (Edited)
well good news is i found the problem, after many calls to my local oil company who we purchased a service contract for our boiler from. A Tech diag. the problem to a bad coil. he showed me the cold water in and hot water out pipes and the water would start out hot but die down. The shower is just using too much water where the faucets are using just the right amount for the coil to supply hot water to them. He also suggested maybe replacing the whole boiler at this point, which he estimated off the top of his head at around 6k.

But now the question is stick with oil or go electric? whats cheaper int he end? what makes more sense now? Any input on this?
 
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