Domestic Hot Water Temp Issue

BoilerLife Posted By BoilerLife, Jan 25, 2019 at 11:40 AM

  1. BoilerLife

    BoilerLife
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    Jan 25, 2019
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    Hey Folks,

    We have had our new boiler (Heatmaster SS G200) hooked up and running since this past October 2018. The house heat and hot water was perfect for the first 3 months, now about 3 weeks ago, the DHW temp has dropped which also is resulting lower hot water pressure and my wife complaining a lot. (cold water pressure is fine). The house heat is fine and thermostat holding temp feeling warm. Could anyone offer any suggestions on what the issue could be with the DHW temp? Keeping in mind I am new to this. Here's some info below on setup.

    -Heatmaster SS G200 OWB (210,000 BTU/hr - 195 gallons)
    -Run is approx. 250' one way (approx 500' total)
    -outside lines are below 4' frost line, probably 5-6' - well insulated rated at -50C
    -using 1" pex in house, and off of circulating pumps which are located in the back of the boiler
    -the boiler mixing pump is Grundfos UPS15-58FC - 3 speeds (set to Medium per manual for G200 model)
    -the main circulating pump is Grundfos UPS26-99FC - 3 speeds (currently set to Medium)
    -HEX on water heater is AIC LA14-30X
    -there is mixing valve on water heater installed and still set to hottest setting - 160F - so no cold water should be mixing in at warmest setting I think, plus it's new
    -water-air exchanger in furnace I don't have spec. info on, house heat is fine though
    -fuel is mostly Oak with 15-20% mc
    -on Well for water and main well pump is set to 35/55 psi (was fine when hot water coming in was really hot)

    -boiler temps/timings are still at factory settings below:
    Set Temp: 180F
    Differential: 10F
    Low Temp Shut down: 140F

    Timer Settings: only happen after burn cycle to 180F, then timer settings reset too if water temp calls for heat based on Differential.
    On Delay: 90 minutes
    On Time: 3 minutes
    Off Time: 30 minutes

    Note: High Limit Switch - cuts power to fan if temp rises above 190F - I don't think this is adjustable.

    At first I thought the DHW temp drop was due to colder temps outside as we did have a cold snap, (-20C, feels like -30C, etc) but it's warmed up now (-8C feels like -16C) and the other day had a thaw of +4C - same issue with hot water - feels luke warm from shower/tub and washing maching with very little pressure. The sinks are a bit warmer, but nothing like it was before this issue started about the beginning of January 2019. Before, the hot water in shower was scalding on full hot, and we would have to turn down a bit with shower tap, which adds bit of cold water, which kept the pressure up, and water was still very warm and comfortable. Now we put shower tap to full hot, feels luke warm, weak pressure, wife complains. When the issue started, main circ. pump was on High for cold snap for about 2-3 weeks - I thought maybe I had too much flow (no idea if that is a possibility, just guessed), put back to Medium last night as that was what it was at for Oct, Nov, Dec, when everything worked great. Issue is the same for DHW at Medium, again house temps feel fine. The Boiler is reaching temp of 180F no problem it seems.

    Suggestions? Thanks for reading if you got this far. Unfortunately my dealer who installed sucks at getting back to me, probably sipping drinks in Mexico with all his boiler money. I wanted to give as much details in first go - I don't have a temp gun right now to take proper temp readings, but the lines feel hot everywhere, supply/return in house and out at boiler - no lines feel cool. I know that's not much help.

    Some initial questions I've been wondering about for my troubleshooting are:

    1. what should my main circ. pump (Grundfos UPS26-99FC) be set to based on the above setup info?

    2. not sure if this even matters, but the cold water intake valve hooked up to HEX, then into bottom of water heater, should that be open 100%, 50%, 25%? Thought here is that cold water is passing through HEX too quickly to get properly heated...or is that not an issue and it should be open 100% meaning that water would come in to HEX between 35 and 55 PSI?

    Any help appreciated.
     
  2. Eureka

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    Honestly sounds like your DHW heat exchanger might be getting plugged. It shouldn’t happen so fast but can clog up in a hurry with debris from initial startup. The installer should have put a Y strainer right before the HX inlet to catch any debris or sludge. When I fired my system up in October I was shocked at how much crud (Teflon tape, pipe dope, brass shavings, silicone, etc) I pulled out of the y strainers a couple days after startup. I’d investigate that first if it was all working fine before. Mineral scale is another possibility but it would take some very hard water to foul it in a few months.
     
  3. Eureka

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    I’ll also add that my DHW is setup as on demand only and cold well water goes through a 20 plate exchanger at full pressure and we have unlimited 135 degree mixed down water.
     
  4. BoilerLife

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    Thanks - I was reading about these plate exchangers getting clogged - I didn't continue with that route because it is so new and our well water here isn't that hard. I never thought of all the start up crud/sludge that you are mentioning though and no, there is no Y strainer installed. Maybe this is the issue.

    While I troubleshoot that route, in your opinion, should my cold water inlet valve be open 100% to HEX/Water Heater and what speed do you think my main circ. pump should be set to? (low, medium, high).
     
  5. maple1

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    If the rest of the system is still fine (heating the house as it always did), I would suspect either the DHW mixing valve, or the HX. Could be install debris in either, as suggested above.

    Some accurate temperature measuring should tell where the heat is and isn't going.
     
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  6. maple1

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    If it was fine before, and not now, and no settings or valves etc. have been changed, I would not change them now. Might make trouble shooting harder.
     
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  7. maple1

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    BTW some mixing valves don't seem to work very well for all that long. Can you put some pics up?
     
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  8. Eureka

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    I’d think your cold water inlet should be open 100% to get full flow at the taps. If it’s partially closed you’d get the pressure reduction you’re seeing at the hot taps. But wasn’t this all working fine before? I’d also think your circulator is ok on medium if that’s the case. Generally you try to tune the OWB circulator flow to give you the desired delta T (difference of temp coming in/out) for your system, around 20-30 degrees. I’d really just try to focus on the DHW water issue if that is all you’ve noticed a change in right now.
     
  9. Fred61

    Fred61
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    Do you have a Whole house water filter at the point where your well water enters the house?
     
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  10. BoilerLife

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    Thanks guys. Troubleshooting has been a bit confusing since I have changed a few settings around here and there. Here's a better timeline of changes.

    October, November, December - main circ. pump - Medium - cold water inlet about 75% (this is how it was after dealer finished I noticed, valve is tight, feels hard to turn, he probably thought he was going to break it, so left it there) - Mixing valve on water heater, warmest setting (160F - so is that fully closed, no cold water in?) house heat and DHW both GREAT. (outside temps mild - normal cool values for season)

    Beginning of January - main circ. pump - High (thought to do this for cold snap approaching), cold water inlet - this is when I noticed it wasn't open fully, so I opened 100%, Mixing valve on water heater, warmest setting (160F) - house heat GREAT - DHW - NOT great, start of luke warm/low hot water pressure issue. (set like this for about 2-3 weeks - pretty cold to normal cold temps with 1-2 abnormally mild days)

    Now (made these changes 1-2 days ago to try and fix issue before discussion of clogged HEX started): main circ. pump - Medium, cold water inlet - 50% (thought here was it was flowing too fast through HEX to heat up - just guessing), Mixing Valve - warmest setting still (160F) - also topped up boiler with water, was down a bit - house heat GREAT - DHW - NOT great, same temp/pressure issue described above in beginning of Jan.

    I don't want to focus too much on the hot water pressure, as I know it's directly related to the hot water temp, before when water was VERY hot, in shower, we would turn down (not on full hot tap setting), so this mixed in a bit of cold water into the shower, which kept pressure levels up - water was hot enough to take some cold, and still be hot, keeping pressure up if that makes sense.

    I'm going to put the cold water inlet valve to 100% open, as it seems like that's how the system should work...when working properly.

    Let me know if you want to see any other pics and I'll upload.
     

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  11. BoilerLife

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    Fred61 - I'm not 100% on the well setup unfortunately - we have only been in the house for 3 years, and details on the well when moving in were minimal, I thought I remembered mention of a UV filter and some kind of filtration system in well before it enters the house - but I don't have any documentation. The only tests I do are for Ecoli.
     
  12. maple1

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    Yes, that is the type of mixer that seems to not last well. For some reason. I have one. It ended up being bypassed not long after I got my system up. Also had one on my old system. I took it right out.

    'Cold water inlet' that you adjusted - can you elaborate? Is that a valve on the input to cold water mixing leg only?

    Sure sounds like there is not enough hot water going through the mixer, leading to both a temp & pressure drop in DHW.

    (You're sure you turned the mixer the right way - right? Fully CCW?)

    Again, accurate temp measuring at all the ins & outs of the mixer & HX should tell where the heat is & isn't.
     
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  13. BoilerLife

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    Okay, so I better understand how this mixing valve works, when fully CCW on warmest setting (160F), does that essentially mean the valve is 100% closed not allowing any cold water to be mixed in with the hot water from tank(when working properly)? Yes, it is fully CCW on warmest setting, attached another pic, can zoom in and see set point resting fully on the stop pin in CCW position.

    Cold water inlet valve, is just the main valve which controls cold water intake from well to fill up water tank, and now in this case, HEX attached first, then hot water tank. I attached a picture - valve at top. (cold water in for HEX/water tank)

    I will have to buy something to take some temp. readings - what would you suggest?
     

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  14. maple1

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    An IR temperature gun is likely easiest to do multiple spots with. But you need to be careful with it to make sure you get accurate readings. They don't measure shiny surfaces good so spray some flat black paint where ever you want to measure. Take many readings in the same place for repeatability, and mix those up with readings at places where you know the temperature. Like at the base of a temp gauge. I think mine does better if I hold it right up to or close to what I'm shooting.

    I'm not sure on the internal workings of the mixer. But it has a thermostat, and the guts can be taken out of it for cleaning or replacement. Google the install instructions for it. If you can valve all 3 legs off, I would consider doing that & taking it apart & checking for something in it. Would be easiest first thing to check.

    That is, aside from checking all temps first. Still possible the HX picked something up too.
     
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  15. maple1

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    Not wanting to confuse issues or get scattered with possible ideas here, but on re-reading I am not sure on your DHW setup. Usually a FPHX would have a circulator on the DHW side as well, to recirculate the DHW tank water & keep it hot. But I don't think you mentioned another circ for that? So is it functioning as an on-demand type of setup?

    If so, the main boiler loop supply temps could be playing a part here also - they may have dropped for some reason.

    Do you know what they are or have been all along? It is all one loop? Temp guage in it? They are good, the more the better.

    How is the main boiler loop configured? I.e., what all does it go through and in what order after it comes into the house? If the DHW exchanger is at the end of the loop, and your house heat is pulling more heat from the loop with colder temps, that could be playing a part also.

    Also still not sure on 'cold water intake valve'. If that is simply the main shut off for the entire DHW circuit, then it should be open fully, all the time.

    Still needing good temp data though. But now maybe in lots more places.
     
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  16. BoilerLife

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    There is no circulating pump on the DHW side, so I suppose it is acting as an on-demand type setup, yes. (dealer setup and installed all this, not me, I'm not an expert). The water tank is electric, with both thermostats for elements turned down, approx. set at 55C (131F)...it has power running to it, but does not kick on, as water temp from FPHX is still above that 131F.

    I don't have a temp gun right now. The only temp I can confirm is what the boiler controller shows...which is always somewhere between 160-180F. All the return/supply lines at house and behind boiler at pumps are hot to the touch, can't hold any without feeling like being burned...nothing feels cool. The FPHX feels very hot, and so does the water-air HX in furnace.

    Loop: comes about 200ft from Boiler to house foundation, then once inside approx 12 ft first to FPHX on DHW, then from there 20 ft over to furnace water-air HX, then 12ft back out to exiting house, then approx 200ft back to boiler.

    Yes, cold water intake valve is the main shut off for the entire DHW circuit - that is what I meant. It is now open 100% - just did that.
     
  17. maple1

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    Loop: comes about 200ft from Boiler to house foundation, then once inside approx 12 ft first to FPHX on DHW, then from there 20 ft over to furnace water-air HX, then 12ft back out to exiting house, then approx 200ft back to boiler.

    That sounds like there shouldn't be a loop problem then.

    Since this is a new system professionally installed, I would be tempted to just get the installer back out there & see what's up. Should be an easy diagnosis & fix for a pro.

    Still always good to have a temp gun around though - they can be good entertainment sometimes if nothing else.

    Also on the HX & DHW - I also have one. Tied to my electric tank heater. Sounds like almost the same setup. But I have a small recirc on the DHW side. A B&G Ecocirc. It pumps a loop on the DHW side of the HX pulling out of a T at the bottom inlet of the tank & sending back into the blow off valve fitting up high (I put the blow off valve in a T). It is controlled by a Johnson A419 temp controller, with its probe just stuck in against the tank wall at the bottom fill fitting. When the tank temp cools off to <whatever> there, it starts the circ. When it rises 20°, it stops it. There is a light switch on all of that that I just turn off in the non-heating season when not burning wood. Adding a circ like that will truly give you unlimited hot water.

    But, if you were getting all you need before, the on-demand approach should work.
     
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  18. Bad LP

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    As for your flow rate can you install a pressure gauge on the DHW side? Does it drop when the HW valve is opened then slowly build up pressure when closed?

    Without a strainer you could have pushed some crud into the HX.

    In my own case I have a 10 micron whole house filter but it was done to protect my ceramic faucets.
     
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  19. Fred61

    Fred61
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    I have a 1 micron filter downstream from the pressure tank on my incoming well water which plugs up quite rapidly lowering the pressure in my water system. The first place I notice the pressure drop is at the hot water spigot. The higher resistance of the lengthy plumbing and in your case the tempering control slows the flow more in relation to the cold side.
     
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  20. BoilerLife

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    In the process of hopefully getting the installer back out here to take a look at the DHW...problem is not sure if I have full faith in his work now if he didn't even think to put in a Y strainer, or a better quality mixing valve - also after reading the manual, it talks about having air bleeding valves installed to let air out of the system when required...he did not install any of these either.

    That sounds like a good setup on your DHW with the recirc pump. If I get this resolved, I'll see how well the on-demand is performing in this cold weather...if it's not cutting it, I'll look into that, hoping to just have on-demand work properly and be hot enough like the first 3 months.
     
  21. BoilerLife

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    Thanks for all the tips and comments, I will update this thread once it's hopefully fixed with the resolution.
     
  22. BoilerLife

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    Update: Water temp is hot from on-demand FPHX. The thing that was throwing off my testing/troubleshooting was I was just focusing on main shower/tub as that was the worst spot with no pressure or flow and was luke warm. Took apart faucet and removed safety hot water plastic thing. The water is now hot, still very weak flow/pressure hot water only.

    Had a good conversation with a new dealer. He didn't see the setup in person and is just going by what I explained to him - he isn't located that close. He is leading me down the route of FPHX being clogged on well water side like what was mentioned above. If the FPHX is clogged on well water side, would this disrupt the flow so much that the hot water pressure would drop like I'm explaining? (I thought if it was clogged like that, it would more so affect the temperature as scale could act as insulator so cold water wouldn't heat as well...or would it also affect the flow/pressure? The water is hot remember...just hot water pressure/flow is down...I incorrectly described luke warm water before because of the safety setting in tub faucet). Dealer suggested a by-pass installed @ heat exchanger so it can be cleaned easily with CLR. I was trying to write down notes, but does anyone have any more details or instructions they can provide on this? I'll be relying on local plumbers that I am familiar with to do this job, so I need to explain it to them. I want to phone them tomorrow hopefully.

    Also, after having it cleaned, if that fixes the issue...great. To prevent in the future again, obviously I will need some sort of water treatment (water softener, whole home filter, etc) - I just don't want a water treatment company to hose me on all their products...I only want to get what I need to resolve the issue. Where should I start with this? I don't know too much about water, or my Well and what (if any) filtrating systems are already down in it outside. (no home filter system inside the house at all). I always thought our water was soft...can you have soft water, but also still have something in it that can cause build up?

    Thanks in advance.
     
  23. maple1

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    Yes, it could & would likely restrict DHW flow.

    Is the DHW flow slow from all the hot water taps? Or just that one you took apart?

    It might not be from scale buildup, it could also be crud/debris from the install. Like bits of teflon tape. Or something.

    A plumber should be able to figure out what to do, easier that I could explain it. But you'd want isolation valves on each of the lines hooked to the HX. And between those valves & the HX, you'd want to T-in hose bibs that you can hook hoses to for flushing it out. One hose would be the output from a small pump. The other hose would be to drain into a bucket the pump is pulling from. Small pump recirculates your cleaning solution through it. You could also T in bypass lines on each leg (just a connecting pipe with another ball valve in it, pipe being T'd in on the side opposite the HX from the first mentioned iso valves) so water would bypass the HX while you are doing that, if you want. Or for if you want or need to bypass it for some other reason.

    With an easy setup like that, I would likely just flush periodically rather than going whole hog on a water treatment setup. But it wouldn't hurt to get your water tested to help figure things out. Seems that would be a pretty fast buildup from water quality so kind of doubting it's that. I have been going on 7 years & haven't touched ours. But I have sediment filters at the outlet of my well pump, which I think help at least for ours.
     
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  24. Eureka

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    I’d recommend putting in a whole house inline water filter while you’re at it. They’re inexpensive and easy to install. Filters are available at home centers. You wouldn’t think you’d need one until you saw what a used filter looks like that comes out of one after a few months.
     
  25. BoilerLife

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    The DHW flow is slow from all the hot water taps. The worst areas are the main shower/tub and the washing machine.

    The new dealer I spoke with said he has never installed a Y-strainer on any boiler setup he's ever done, and really didn't think FPHX was clogging on boiler side...said well water side, but did mention that's a fast build up - I hope we are going down the right path. (our sinks do get a white residue on them, and so do the shower faucets, coffee maker, kettle, etc and we clean our with CLR or vinegar now and again...but the water is soft - so sounding like it's some other kind of sediment in the water?

    Okay, I will pass that setup idea to the plumber, I spoke with him this morning, but he can't come out until next week unfortunately.

    Ya, I would guess your sediment filters make a big difference in your setup. The plumber said he would test our water for hardness and iron. I'm sure our water is pretty soft, so I don't want to get a water softener if we don't need one, but there must be sediment in it...likely will go the whole home filter route just to prevent this from happening in the future again.

    On a separate but related note since we're talking about wells and filters....we don't have any extra filters here in-line, no filters of anything (just a brita filter water jug in fridge, and fridge water filter)...our bacteria test I do twice a year (Spring/Fall) always comes back 0 bacteria...would it be a waste of money to put in any kind of UV filter, or other water treatment for bacteria (reverse osmosis, etc) when we likely get the sediment filter installed? I am just being extra cautious about this because we do have young children, and since we'll be installing sediment filter anyways...are UV filters, reverse osmosis, etc expensive? Now that I'm thinking about it, isn't reverse osmosis for removing chlorine taste?
     

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