Sorry for the long post, but it's a compilation of notes that I've had for a bit now.
I have a weil-mclain gold oil boiler with a weil-mcclain gold 38gal indirect hw heater. Both showerheads run at close to/less than 2.5Gal/minute.
I seem to be running out of hw way too soon. Never had the problem all summer/fall while the house heat was off.
Here are recent notes from today so that are at the top of this long thread:
House heat was probably on much of the night. Dishwasher ran around 3pm. First shower at 6am was lukewarm from the start, then got cold. Second shower was cold the whole time. I checked during the second shower and it was NOT calling for heat. I turned the dial on the hw heater up a bit and it started calling for heat. I had to turn the dial way down into the cold section (the area where I know there's no HW in the tank) before it would stop calling for heat.
I been taking some notes since 12/10 and have had 2 people from the oil company out already to look at it.
Seems logical to me like the hw heater isn't storing enough hw or it's not calling for hw soon enough, but I really don't know how this works.
Tested water before bed and it was extremely hot.
First thing in the am, I turned on a faucet and the water was extremely hot.
First shower was about 3 minutes long and it stayed hot
After that shower, I took a look and the hw zone was NOT calling for hw and another house zone was
About 5 minutes later, 2nd shower started and it got cold after less than 5 minutes
During the 2nd shower, I noted that hw zone was still not calling for hw and the other house zone was
A few minutes after the shower, i checked again and the hw zone was calling for hw now
About an hour later, the 3rd shower started and hw ran out after about 5 minutes
No zones were calling for hw right after that shower
10 minutes later, started water running at faucet and water was just lukewarm
Checked again and no zones calling for hw
5 minutes later, started water running at faucet and water was still lukewarm
First person out on 12/11 didn't fix it. He did something with the relay on the HW heater and then we ran the water and he showed me how it started calling for HW heater after a bit, so looked like it was properly making new HW.
He did say the hw heater isn't set up for priority, but that the boiler was sized well and shouldn't be a problem. Logically (and that's all I can go by as i don't know this stuff), I don't see how priority would be an issue based on what I'm seeing. Here are the notes from today.
Heating zones were probably off and on a bit during the night as it's unseasonably warm here in NY today.
First shower ran out after about 3-5 minutes
Didn't check to see if it was making hw
Set both other zones low to make sure they weren't calling for heat
2nd shower was good for full 5-7 minutes
Checked right after that shower and it was calling for hw, but only for a few minutes
next shower was about 10 minutes later (hw heater was not calling for heat before the start) and had hw for about 5 minutes and then it was lukewarm after that. It did stay lukewarm and not get cold though.
Checked right after that shower and it was calling for hw again.
Something clearly is wrong. To me, it seems as if the hw heater isn't holding enough hw. If I have a 40gal hw heater, how is the first shower of the morning hot for less than 10 minutes? There would have been plenty of time last night where the other zones weren't calling for hw that the hw heater would have had priority to full up. Should the hw heater always be holding nearly 40 gallons when idle?
Second repairman came out and blamed it on too high a flow from the showers or a mad mixing value somewhere in the house. I measured the flow and both showers are probably right around 2.5Gal/min or slightly less.
Seems to be worse when it's cold, but this morning I caught a clear problem. House heat was probably on much of the night. Dishwasher ran around 3pm. First shower at 6am was lukewarm from the start, then got cold. Second shower was cold the whole time. I checked during the second shower and it was NOT calling for heat. I turned the dial on the hw heater up a bit and it started calling for heat. I had to turn the dial way down into the cold section (the area where I know there's no HW in the tank) before it would stop calling for heat.
I need to have them send a 3rd guy at this point, but just hoping someone has some ideas on a direction that I might lead him in. Or maybe someone can give me some better ideas as to how to monitor this more logically so that I can explain to the oil company what's going on better.
Thanks in advance!