Hot Water Problems

David_16

Hello,

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.

12/10
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

12/12
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?

12/15
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.

12/21
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!

Jamie Hall

Not my area -- but some suggestions anyway...

The 38 gallon tank is always full. The question, of course, is with what? There should be a control which senses the water temperature in the tank and, when it is low, circulates water through the boiler (and turns the boiler on, if necessary) to heat it up. The priority bit means that if the storage tank needs to be warmed up, circulation is stopped or reduced to the heating zones and is fed through the hot water tank instead.

This is, clearly, a control problem with the temperature sensor for the hot water not calling for circulation and/or not calling for the boiler to fire. Something isn't set up right.

David_16

Thanks much for your comments. The repairman today thought it was the aquastat on the hw heater and he replaced it.
Hopefully that fixes this.

Is priority a "bit" or is it a way of piping? Is there a way to tell if my hw heater is set to priority?

Jamie Hall

Priority is a setting on the controllers. As I understand it, the easiest way to tell if it is set is to see what happens when the system is calling for hot water -- does the heating circulation stop or reduce, or keep going?

David_16

I'm pretty sure I do not have a tempering valve on the indirect, so I will not crank up the temp.

Here's a picture of the inside of the taco box. HW heater is zone 1 (top red light), but seems to me that according to the description on the circuitry that it's not set for zone 1 priority (it says to remove that first jumper). The 2nd screw is P and the 3rd screw is ZC.

First of all, almost no chance I'm doing that unless many people say it's safe.

Would changing it to priority provide more domestic hot water faster when other zones are on?

I'm still hopeful that changing the aquastat fixed the issue. Remember, in the original post, I noted that this morning, there was clearly an issue of something not calling for heat when it should, but I've seen other mornings where there was hot water, but only a few minutes worth and it did wind up calling on it's own without my intervention.

Also, this seems to be a problem every so often in the winter. All was working great until it started to get cold.

David_16

So in the winter, if we are taking showers back to back, the water may never run out if priority mode since the boiler is using all resources to make domestic hot water, but if it's not in priority, it make take longer to recover?

I really don't recall this ever being a problem in the summer, but it seems to pop up in the winter.

I think, if I recall correctly, the other day, I had turned the house heat off and it was still running out of water quickly, so that still may be the aquastat issue that hopefully is now fixed.

I don't see any real negative to priority though. If the house isn't heating up while people are taking showers, that doesn't seem to be a big deal.

What about an outdoor reset? That's not required if I were to set priority to the hw heater?

Interested to see additional replies. Like I said, not a chance I remove that jumper unless I'm 100% sure it'll be ok.

hot_rod

The important thing with priority is that it "times out"
If you have a long DHW load time, or the indirect starts liming up you don't want to risk freezing pipes because you are stuck on DHW priority.

Every winter we hear of frozen hydronic systems, it can happen.

Most of the newer relays have a 60 minute DHW priority function.

Try the system with the new stat before you make changes.

David_16

The boiler is a Weil-McLain WGO-4 so I guess it's 126K BTU. If I were to turn down the heat to the other 2 zones, it should be able to keep hot water running indefinitely?

Very interested to see how tomorrow goes with the new Aquastat.

RJMCTAFO

Hat

I think hotrod meant that in the case of a failure with the indirect ( bad pump etc. ) the priority will never kick off. Had this happen to a home this past winter and the coil in the 2nd floor air handler froze because the priority locked out the heat zones from operating due to a faulty zone valve.

To the OP
That boiler and indirect should provide ample hot water in your situation.

David_16

Warm out today so boiler didn't run much last night, but so far, so good.

1st shower was 5-10 minutes or so and remained hot. 2nd shower was maybe 15 minutes later for 5-10 minutes and stayed hot (said it started getting less hot at the end, not sure exactly what she meant). House heat was probably off during this time.

About 45 minutes later, heat house definitely been off for a while at this point, I took a shower and let it run for 15-20 minutes and it stayed hot. I did have to adjust the dial (it's a single dial) a couple of times to keep the temp up, but it was still hot enough for a good shower at the end.

About 20 minutes later, I cranked up the heat house, waited about 5 minutes and then and ran the shower for about 10 minutes. It was still plenty hot by the end.

I guess that's how it's supposed to work. I guess the need for priority can be tested with my last 2 tests. Though if the 3rd zone was also on, maybe it would have taken too much away from the DHW at that point.

Anything else I should test out?

Seems like the aquastat definitely improved things, but will have to see what happens when it gets cold again. I'm on Long Island by the way, so you have an idea of the climate I'm in.

Thanks again all!

hot_rod

Keep in mind incoming water temperature drops, in some areas a lot in the winter, so expect performance to drop in winter.

RJMCTAFO

Never condemned priority. Use it whenever possible. But with new controls they have priority override. Old controls do not. If I come across an older boiler with no override in the control I explain to the customer the possibility of an issue. I then ask them if they leave the home for multiple days during freezing temps. If so I turn off priority.

Cheap insurance that typically does not affect HW performance.

RJMCTAFO

My concern is not strictly limited to the indirect pump or ZV failing.

If the burner fails with a control that has no priority over-ride it only runs the pump for the priority zone=possible frozen pipe.

If the burner fails on a control with priority over-ride all pumps run constantly. Only caveat being that the aquastat does not have a low limit wired to shut down the zone panel via ZC/ZR.

It is amazing how many boilers I find that are set to maintain when there is no logical reason to do so. Especially when all the new aquastats can be set to cold start with the turn of a dial.

rick in Alaska

I have had more than one aquastat fail like you said and was my first guess from what you were describing. I will bet your problem is solved.
Rick

David_16

Had a couple of very cold days here now and everything seems to be working right. No one complaining about AM showers. I guess it was indeed a bad aquastat.