Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

Navien 240 combi installed - I have concerns

TdubxTdubx Member Posts: 16
I just had a navien unit installed along with new pex piping and additional radiant in a back room. I've read a lot of posts that say I can run 2-3 showers with this unit. That's not what I am getting.

At a set temp for domestic of 135, I can barely take a shower with the kitchen tap running.

The radiant is not on at that time either. I don't have a recirc pump installed either.

All pex lines, except for what's near the navien.

A few questions:

Curious, what people paid for professional installs?

Am I missing something or setting somewhere?

If I add a recirc line, will that shorten the life of the unit?


  • SnowmeltSnowmelt Member Posts: 751

    The 240 is there bigger unit

    There are a few issue on what's going on.

    Did you call navien yet?

    What's the water temp coming in?

    How many gpm do you have?

    Are you losing water pressure?

    Do you mix a lot of cold water, do you have it that high for dishwasher. If you have water temp down to 110 I bet it would still be hot.
  • heatpro02920heatpro02920 Member Posts: 991

    We aren't allowed to talk price on this site...

    Did you call your contractor?

    Can you show us a picture of how its piped?

    Also get us the gpm reading on your shower nozzle..

    With a tankless system you want to be able to run your shower and faucets full hot with no cold mixing... Some systems and designs dont allow for this, but to me its ideal... 135 is too hot IMO, my tankless is set to 115 and 110 in the summer months...
  • TdubxTdubx Member Posts: 16

    No, I have not called them yet.

    Temp in is: 76

    Gpm: 2.4 with the tap on or off. Could it be the line into the house? It's only a 1/2"

    I lose pressure when I use more than one appliance or tap. I had the same issue as before, with my water boiler, but nothing like it is now.

    Yes I mix hot and cold. The guy who installed it has his water at 120. Maybe lower temp would be better?
  • TdubxTdubx Member Posts: 16

    I'll speak with my contractor tomorrow.

    Attached is a pic.

    Not sure about shower nozzle Gpm. It's a wand style. Waterpik brand.

    I changed my water to 120 for now.
  • GordyGordy Member Posts: 7,122
    1/2" waterline

    Is the problem. Are you sure about this?
  • HomeOwner1HomeOwner1 Member Posts: 134
    We have 3/4 off well pump as water supply

    Our setup does indeed supply three showers with newer shower heads with the CH-240 unit we have running.

    Our supply line for water is much larger than yours though. We have a 3/4 supply line going directly into the unit.

    We also have our unit set to the well pump setting. Not sure if that is applicable on the newer units.

    Good Luck.
  • SnowmeltSnowmelt Member Posts: 751
    edited March 2014
    1/2 line

    I'm going with Gordy the 1/2 line is to small. In my house, the water line was 1/2 everywhere when we redid the kitchen that is when I. Had a chance to redo the water lines going in the wall. I I only wanted to do this once so I took 40 feet of 1" pipe then broke down to 3/4 then 1/2 at the fixture itself.

    Before when I was in shower I was in shower and flushed the toilet the shower loose pressure and became ice cold. Now I have shower 2 sinks and still flush toilet and get just a small pressure drop but no hot water loss.

    I don't like that set up, you don't need the pressure reducer and your suppose to use there own port for water going into the boiler. Also is the spiral vent getting air as water comes in or is it catching all the air every time it goes around the loop.

    There are 5 water ways 2 for heat 2 for domestic water and 1 for boiler feed which is 1/2".
  • TdubxTdubx Member Posts: 16
    1/2" Line

    Yes i am sure about the 1/2" line. The houses in my area were all built that way and some of my neighbours have ungraded them from the main to a 3/4".
  • TdubxTdubx Member Posts: 16

    I'll check the unit for a "well pump" setting. Unfortunately there is nothing I can do with the 1/2" line unless I dig up a new run from the main on the street to my house; which I am almost tempted to do at this point to get my shower not to lose pressure.

    For me, I dont lose heat, just pressure, but after I run a tap, the shower barely stays on, but it does stay hot.

    The new pex that we ran in the house is 3/4" runs, down to 1/2" to the taps/appliances, so I doubt it's the new piping. Something tells me more and more it's the pressure from outside the house.

    Also, no one commented on my thoughts about a recirc pump shortening the life of the units. I read a post claiming that indeed it does just that since the it'll put more stress on the unit.
  • SnowmeltSnowmelt Member Posts: 751

    I would invest in 1 inch cooper and install that everywhere you can. Also get a 1 inch sediment filter (clear filter housing) the more one inch line you have in basement the better your water pressure would be. It's all about volume .
  • TdubxTdubx Member Posts: 16

    I keep re-reading your post but it's not clear to me what you've done. Can you re-explain.

    Are you saying, you ran 1" lines in your house, down to 3/4" then 1/2" to the fixtures? [That's a similar setup I have.]

    i dont get the same effect you do with the heat loss, mine's purely pressure drop.

    What do you mean by your 3rd paragraph "i don't like that setup..." it's not clear to me what you're saying there.
  • SWEISWEI Member Posts: 7,356
    1/2" mains

    that I have seen were installed before WWII.  Run hard water through them for 60+ years and you get something more like a 3/8" line -- or worse.
  • TdubxTdubx Member Posts: 16
    1" line

    I just had my lines re-done in the house. You're saying that PEX isnt good enough, and that the pressure from a 3/4"->1/2" sont suffice?

    I should also note, I am in a rancher house (1300sq ft) with radiant flooring that only touches 1000 sq ft of that area.
  • KC_JonesKC_Jones Member Posts: 3,172

    Just another homeowner here, but I will add the 1/2" is suspect.  I have 3/4" coming into my house, but the previous owner redid the whole inside with 1/2" everywhere.  Just having the 1/2" inside the house caused major pressure issues.  I had the scalding shower toilet flush issue.  I redid all the main "trunk" lines in 3/4" copper with 1/2" going to fixtures and it completely cured all the problems.  i can now pretty much open anything flush any toilet and not affect the other appliance (that a human can notice).  In my opinion 1/2" just isn't up to supply a whole house from my experience.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • SWEISWEI Member Posts: 7,356
    PEX is fine

    As long as it's sized and installed properly.  Underground, it's far better -- especially in acidic soil.  Watch out for the fittings and rings in that case.  ProPEX EP fittings and rings have higher flow and are immune to corrosion and dezincification.  You'll need PEX-A pipe to use them.
  • SnowmeltSnowmelt Member Posts: 751
    Well tank

    What or should I say what size water tank do you have. Your well tank will be around 40 to 60 that will be the cut in and cut out. It's all about volume if I was using pex I would go 1-1/4 to the first few fixtures and to the water heater it sellf .

    For now I want you to just put all the hot water on and et the gpm off the remote.

    You can't really change water pressure coming in the house or at the tank, but what you can change is the volume of water after the water filter.
  • TdubxTdubx Member Posts: 16
    Contractor and pressure.

    I just tested - 3 taps open on Hot only (kitchen faucet, bathroom faucet, and tub faucet) i was only getting 3GPM. I just had my contractor come over and he said for sure it's the service coming into the house. So looks like I may need to start doing some digging!

    Any thoughts on the recirc line shortening the life of these units?
  • icesailoricesailor Member Posts: 7,265
    Another take on your problem:

    Here's another take on your problem.

    First of all, that is a really nice professional installation. Be proud that you hired someone that knew what they is doing.

    You need to get something (or someone) to check the static (nothing running) and the flow (something running) at the water in the house. You have town supplied water. Piping houses with 1/2" copper is wrong, but if you go by the fixture unit valves in piping, it is OK, but you still need a minimum of a 3/4" water service where it may split and go 1/2" each to the water heater and the hot water, If the service entrance is 3/4" and reduces to the whole house from there, it is wrong. Put a pressure gauge device on the service entrance and measure the pressure, If it is under 40# static (not flowing), it will never work properly. If it drops below 30# when flowing, it will never work properly. If you have a single lever pressure balance shower valve, it will never work properly because the valve is constantly doing its job and protecting you by trying to balance the hot and cold water. If the Navien is set to 120 degrees, it probably can't over come the lack of hot water pressure and the volume of cold water.

    If you want, the easiest way to solve your pressure problem is to install a booster pump on the water service as it inters the house. You can buy stand alone units or make up your own. But it will raise the pressure and volume available in the system. Remember, when you raise the system pressure by sucking on a water service, you are theoretically increasing the street pressure by making the system use atmospheric pressure to push harder on YOUR system. Mother Nature HATES a vacuum.


    Where do you live?
  • TdubxTdubx Member Posts: 16

    Thanks Icesailor.I'm pretty sure you nailed it on its head here. My contractor is coming back later and putting my system to the pressure test. He said for sure it was the outside lines, as these homes I am in were build just post WWII and haven't had their services upgraded since.

    I live in the Vancouver, BC area, Canada. I'm at the bottom of the mountain so you figure my atmospheric pressure and gravity fed pressure would be good being so low. But that s not the case with my house. I remember speaking to my neighbours last year and they had to upgrade their services when re-doing their houses for upgrades/renos.

    And yes, I am super happy with the install. The guy who did it, has installed over 90 of these units in the Vancouver area and took his time with another friend and managed to install the unit, run new water lines in my house, new radiant lines and washer lines to my extension, add a gas bbq hookup outside, all in 2 days. Very happy.
  • icesailoricesailor Member Posts: 7,265
    Before you dig:

    Before you dig, check the service pressure like I told you in a previous post.

    If you have metered water, where is the meter? At the curb or at the house? Have it checked for flow. It can be "hanging" and not flowing as fast as it should. When the house was built, did they use 3/4" poly pipe? Is it 160/200# poly and did they use compression fittings or insert fittings? Some cheap installers back when used some galvanized steel insert fittings that if screwed into a brass  curb stop, will develop rust at the connection and slow the flow. Is there a curb stop just outside of where the water service enters the house? If the meter is at the property line and it is a distance away, is there a bib pressure drop from the meter location to inside the house? It will show that the curb stop needs to be replaced. Or you could have a big rock crushing the plastic/poly water service because someone was too lazy to hand backfill the trench to cover the pipe, Then finish with a machine. If it is rocky soil, it may not have clean sand under the pipe.

    If its a long run, really consider a booster pump.
  • icesailoricesailor Member Posts: 7,265

    You should be able to go to the water supplier and find out what you have for a service. Copper was cheap post WW ll, but if the builder had a surname that is often common in the northern British Isles, galvanized steel was cheaper and would be working fine when the deeds were signed over. If it is galvanized, there is definitely plaque problems with brass valves. Unless the pipe is galvanized wrought iron. If you have high dissolved iron in your water, definitely.

    If you replace the service, go with a minimum of 1" SDR/200# Poly. It will equal 3/4". I always used 1 1/4" with compression couplings to equal a 1" flow.

    If you get the water service fixed, you'll think you died and went to heaven.

    One good way to spot bad services without a gauge is to open a tap that is at the service entrance like a boiler drain, and open it up as wuickly as you can, note if the flow is high and then drops off to a steady, slow flow. Stop it, then repeat it. If the pressure goes back up and does it again, there is an obstruction. Sometimes, you can actually hear the water filling the pressure back. The slower the refill, the worse the obstruction.

    Where I worked, the water provider was a very old company started in the late 1800's.They had records going back to then. If you wanted to find out of an old house had a lead service, you could look in a 1890 service record and see the fittings they used to connect it.
  • TdubxTdubx Member Posts: 16

    I just spoke to the city and my water main was upgraded in 1989 to a 3/4" line from the city side. At that time, the pressure was noted as being 110# at the main. So I basically need to run new lines from the main to the house. Sounds like that is where my pressure problem is stemming from!
  • Paul48Paul48 Member Posts: 4,257
    Not Yet

    As said....Check the pressure in the house. Is there a PRV on the supply where it enters the home from the street? With that kind of pressure at the main, you should not be having the problems you're having.
  • GordyGordy Member Posts: 7,122
    Ditch the 1/2"

    You will never have decent flow to multiple fixture simultaneously until you increase your line size from the main. I don't care how much city pressure you have. I would size 1" since you will be doing it.
  • TdubxTdubx Member Posts: 16

    Yes there is a PRV that is on the line just before it enters the house. I was told to change that if I did my water lines from the main to the house.
  • Paul48Paul48 Member Posts: 4,257

    I guess 22 or 23 GPM to the house would not be enough.
  • TdubxTdubx Member Posts: 16
    Acceptable GPM

    What would be the acceptable GPM. I already know I'm low, but what's a good number to get. Maybe i can get away by just changing my PRV instead of the entire run?
  • Paul48Paul48 Member Posts: 4,257
    I sound like a kid- OMG

    Maybe the PRV is adjusted to 20 psi? Buy a $20 sillcock gauge. Make sure the sillcocks are piped after the PRV, and CHECK  THE  PRESSURE.
  • SnowmeltSnowmelt Member Posts: 751
    edited March 2014

    You didn't give us any pressure yet, go to the plumbing supply house and buy a water pressure guage that you can hook up to your hose bibs or faucets. Then tell us what it is when running then after running pressure is not volume so giving us g.p.m. Doesn't tell us what pressure is coming in home .

    Here is what may be happening, your in the shower and you have 1/2 pex and someone runs another fixture, then your stealing the water in the shower line to feed other fixture. If you increase pipe size you will increase volume of water in line and pressure (running pressure) won't drop as much.

    Your boiler

    Look at bottom of boiler is there 2 one inch tappings for boiler water, 2 3/4 tappings for domestic water and 1 1/2 feed all the way to right for boiler feed.

    Then there is 1 3/4 tapping for gas and 1 1/2 tapping for condensation (ran in PVC)
  • icesailoricesailor Member Posts: 7,265
    1/2" piping:


    It is perfectly acceptable to pipe a house 3/4" and 1/2" copper and the house must have a 3/4" service into the house. And then, a 3/4" pressure reducing valve. You split the copper into 2 halves, one going for the cold and the other feeding the water heater. That way, you have equal hot and cold water pressure and volume on both sides of the shower valve. Good money is on a bad PRV. If you have 110# at the street, and the house isn't on a hill, 100' above the street, 110# is enough to blow a glass out of your hand.

    We always talk about the need for digital combustion analysis on heating equipment. You need pressure gauges to tell you what's up. You need one on the street side and the house side of the PRV. To see if the street side is 100#+, and stays there when t runs, or drops appreciably while running, and see that the house side is adequate for the height of the house and how much it drops.

    For smelly toads sake, all the hot shot plumbers are now running home run 1/2" PEX CTS tube in all the new and old houses. 1/2" CTS PEX has a smaller ID tha 1/2" Copper Tube.
  • TdubxTdubx Member Posts: 16

    Snowmelt - correct about the boiler setup and water. 1/2" lines go to a 3/4" then to a 1". Domestic is PEX all around the house at 3/4" then small runs from the attic to the fixtures themselves. My contractor said the low pressure could also be from rust and debris in the lines that may be caught up in the filter. We have yet to investigate that either. I have had issues with sediment and other rust in my copper pipes and has to constantly clean out my kitchen and bathroom faucets to get pressure back and clean them out.

    The house isnt on a hill, in fact it's at the bottom of one. That pressure test was done back in 1989, but even still, the fire hydrant across the street, from what I'm told, is holding a pressure of 100#. So I too suspect a faulty PRV since the valve and copper has rust and has been problematic before. i dont plan on digging anymore than i need to. My PRV and the line into the house is easy enough to change so i plan on doing that first before any digging.

    Yes, toads are everywhere Icesailor.
  • icesailoricesailor Member Posts: 7,265
    edited March 2014

    If the line coming through the foundation is copper, and what the water supply company replaced was connected to copper (they should know), you do NOT have a plugged up or obstructed copper water service. Unless it is common in your locality, it just doesn't happen and you're not the one. They make inline filters. CUNO makes an excellent one with high flow and replaceable cartridges. I would install them on new well water systems because one driller where I worked, never developed his wells to get all the fine sand and drill mud out of the casing. You sound like you have an iron issue. Like it is precipitating out of suspension and into a solid. There should be a small screw in filter on the water inlet to the water heater part of your Navien. I'm not familiar with Navien's, but all the others I have worked on, have this filter. Look for it. Pull it out and check to see of it is plugged up. Sometimes, you have to blow it with air. But if it slows down the water flow, it turns down the gas flow so as not to overheat the unit.

    As this string goes on, I personally think that you have a service issue and not a mechanical issue. I promise you that if that Pressure Reducing valve was set at 75#, and you got in the shower, it would hurt a lot. Like most people can't take the pressure. Even at 60#, it still hurts in the second floor. And the first floor, you'd be backing off the pressure.

    Check out the filter I am posting (I think). I always connect them up with McDonald MPT X CTS compression adapters for underground use with the big clamp and stainless steel bolt to keep it from blowing off.

    This one:
  • GordyGordy Member Posts: 7,122
    psi, and 1/2" line, and volume.

    Cmon really fellas You need the volume to go with the pressure. Only get so much through 1/2" pipe.

    Paul where are you getting that high of GPM in 1/2" pipe of any type?
  • SnowmeltSnowmelt Member Posts: 751
    Pressure reducer

    Where is the pressure reducer on the boiler, you don't needed one

    For your domestic we don't know what the pressure us yet
  • Paul48Paul48 Member Posts: 4,257
    Not 1/2"

    He's got 3/4" from the main at 100+ psi. The drastic drop in gpm with multiple fixtures can't be attributable to that. I believe he said he had 3/4" with 1/2" to the fixtures. I don't know for sure, but there is the possibility that when he had a tank type water heater, turning the PRV down may have been someones answer to a dripping relief valve, in the absence of an expansion tank. Just a W.A.G.
  • SnowmeltSnowmelt Member Posts: 751

    I think he had 3/4 pex we don't know how many gpm he is using could very well be that. Still have to get a gauge and check water pressure.
  • GordyGordy Member Posts: 7,122
    edited March 2014
    1/2" to house

    1/2" from water meter feeding house either way the distribution line needs up sized to 3/4" min.

    Im confused. By the op Around here when the city recons a street with new sewer, and water new water lines get run to the house. So maybe I'm misunderstanding when he said he had to dig up the line a few posts back.
  • Paul48Paul48 Member Posts: 4,257
    Long Post

    "I just spoke to the city and my water main was upgraded in 1989 to a 3/4" line from the city side".
  • Paul48Paul48 Member Posts: 4,257
    Long Post

    "I just spoke to the city and my water main was upgraded in 1989 to a 3/4" line from the city side".
  • Paul48Paul48 Member Posts: 4,257
    Long Post

    "The new pex that we ran in the house is 3/4" runs, down to 1/2" to the taps/appliances, so I doubt it's the new piping. Something tells me more and more it's the pressure from outside the house".
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!