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Control & Piping Issues With New Boiler-Turbomax (Solved)

D107D107 Posts: 1,580Member
edited April 18 in Gas Heating
Finally had a Peerless MI-03 boiler and Turbomax 45 installed last week. As you can see from the attached photos the work is quite meticulous, I’ve always appreciated the art of many of the installs posted on the wall. The installer went out of his way to use the best materials and make this something that can last many years. Since the Wall helped me so much over the years to get to this point, I wanted to put up some photos for your review.

This is the second boiler install I’ve seen and I’m even more amazed at the great mix of brain and brawn that hvac entails. The amount and variety of components and materials that have to be assembled is staggering. I had hoped to take some videos and photos of the ongoing work but my basement floor was filled wall to wall with everything.

Boiler will have new 5” chimney liner installed this coming week; right now it’s in the old brick internal 33 ft chimney 7x11. Due to a heat loss of only 38K—probably more like 30K—the thought was to use Turbomax as an indirect and buffer, given the microloads of the three zones during the shoulder seasons.





We are having some issues with the Turbomax-Boiler controls. For the problems listed below, the installer is consulting with his technical contacts but I wanted to get some wally feedback to throw into the mix.

Setup:
Temp Range: No ODR. 20º T, 160-140.
Heat Loss: 38K, three zones; MI-03 Fires at 70mbh, Net: 50mbh.
Emitters: Zones 1, 2 cast iron radiators; basement zone baseboard. Series piping for Zone 1 and 2.
(Prior monthly gas usage from stand-alone 40 gal, 30kbtu hot water tank: 8 therms, which represented about 27 hours, or an hour a day--0.25 therm day) of firing.
Hydrostat 3200+,
(3) Zone Sentry Zone Valves Z075T2, with Caleffi circuit setters set to 2gpm each zone. Zones Heat Loss: 18K, 10K and 11K.
1-Taco ZVC-403 ZV control (heating);
Taco SR501 for DHW.
Heat Circ Taco VT2218; ∆T
DHW circ VR1816. ∆P

Issues
1-Wired with the Hydrostat, we found that when DHW only was called, the heating zone valves were opening as well—even without the t-stats calling for heat and so ghost flow was circulating. Installer temporarily solved this by changing some of the hydrostat connections with the TACO ZV relay. So now the zone valves do not open unless there’s a call for heat, but he warned me that his change removed DHW priority, that heating and DHW calls could occur simultaneously which obviously increases the potential load tremendously. He is hoping his tech people will have a way to connect the controls to correct this problem.

We had talked about the possibility of piping the Turbomax as a regular indirect or using the injection system as specified in the manual. This install is apparently a ‘two-pipe’-primary secondary install. I really don’t want to lose the buffer function; adding injection I believe would add a third circ which goes against the original idea of a simple system….(FYI Turbomax Ranco aquastat is wired to the DHW circ to have the it cut in at 150º and cut out at the boiler set temp of 160.)

2-The Hydrostat feature that protects against condensation may need tweaking as well since we’ve seen the heating circ go on at water temps as low as 106. Hydrolevel has a cutout of circulator at 115 and cut in at 125. Doesn’t this seem low? Is that like the Pump Logic of Buderus? Even in this not super cold weather I’ve often seen the return water temps or boiler temp as low at 129, etc. even though if circ could be turned off temp would build quickly.

3- I’m thinking my hot water bills—esp in summer will be higher, keeping the 48 gal turbomax constantly 150-160. Maybe I can change some settings in summer. But hopefully buffer function will save some $$ in winter.

I’m curious to hear some opinions on this. Is Turbomax's recommended injection system the only way out of this?

Comments

  • hot_rodhot_rod Posts: 11,859Member
    edited March 25
    I'm not so sure that ∆T circulator and Quicksetters will work together? The ∆T circ constrains and try to fix the ∆ by slowing flow, the Quicksetters are trying to maintain a fixed GPM Being a manual balance valve I don't think they will maintain a set GPM as flow changes. It seems like the two have different MOs in mind? You may need, or want to set the circ to fixed speed if heating is not what you expect across all conditions. Plus you could run ODR if you eliminate the ∆T operation, set a minimum to supply adequate DHW production.

    For a two pipe buffer to work properly the connections need to be as close to the tank as possible and that short connection piping large diameter pipe, ideally large enough to keep velocity below 2 FPS, at max flow rate, in the short section. That is how the hydraulic separation function needs to work, low flow velocity in the common section of the piping. I'd add checks on the boiler also.

    It is very similar to primary secondary piping in that the closely spaced tees make or break the separation function.

    TurboMax does have a simulator program to show DHW capacity at different and lower boiler operating temperatures. I'm not sure if reps have access, or send the data to TurboMax directly?


    It is a very nice piping job.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • lchmblchmb Posts: 2,946Member
    edited March 25
    Hot Rod, I wish I knew 1/10th of what you've learned over the years.. thanks for the knowledge you share..
  • clammyclammy Posts: 2,316Member
    I m pretty sure that they recommend at min gpm and btu requirements for stated performance . I m sure califee has a nice piping diagrams w a control layout using a dpdt controller to give you tank priority w a hi and low limit with the low limit shutting off your central heating pump . I ve put in a couple of turbomaxx tanks I usually pipe them at a minimum of 1 1/4 w a pump w a chk and a taco flow chk on the return stops all migration . I pondered using it as buffer on a job or two but it didn’t work out w the existing system there wasn’t any benefit . I think personally I would have piped the boiler primary secondary to avoid excessive flow through the boiler and to give you better pump isolation and would have increased the tank piping from 1 1/2 to 2 just in the area where my central heating was teed off . The central heating side also need a pump w a check valve and a chk valve on the return side before tying into the return this will stop any migration . I would also look into replacing that standard aqua stat they give you I usually install a ranco 110 volt electronic temperature control very accurate and you can get in a two stage unit and set for hi low to give you priority to tank charge allow the boiler to fire and add heat to the tank and operate your central heating pump which will cycle on the tanks low limit if that tanks continue drop in temp below your minimum setting .a big benefit of primary secondary your boiler is that when ur safeguard cycles your pump on low limit it only cycles the boiler pump on and off .i would use standard circulator on the tank and boiler and put the circuit setter on the boiler and the vfd pump w the zone valve system . That little mi 3 only needs less then 8 gpm should be piped 1and the tank loop after the central heating should be 1 1/4 . When it all said and done there’s a lot of necessary piping requirement and thought required for it all to function properly it’s just missing a couple of things unfortunately that’s what’s usually pushes those type of installs over the budget for most older home ,you really have to sit down and draw it out both piping and control wiring for it to ever work properly and weigh it out on roi and fuel usage . Great concept as a two pipe buffer hard sell unless using to aid a heavily micro zone hi temp system . As a stand alone indirect they perform great as long as you have the btu s to drive it if you really require that much domestic water and as stated above stay within the required gpm (I believe a min is 10 gpm ) due to the diffusion plate in the tank is part of there design and recovery . Nice neat work I will say just needs a little tweaking on piping and controls .peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • hot_rodhot_rod Posts: 11,859Member
    It's all about the basic BTU formula.
    For example 500 flow (∆T)

    500 X 4 gpm X (110°-50°) = 120, 000 btu/ hr
    Which is what the TurboMax simulation shows.

    In your case with if it is a 70,000 input, 58,000 output boiler, just under 2 gpm is what you can expect with incoming water at 50° raising to 110°

    500* 1.95 gpm* (110-50)= 58,500 BTU

    With a cast boiler like yours you will need to run a minimum return around 130°, so you could run it at a 150°-130, 20∆T

    I think you chose and piped the TurboMax for a buffer?

    With a small boiler output you could pipe the Turbomax as it's own zone and give it priority for DHW.

    It may be tough to keep up with a heating and DHW load concurrently, piped like that.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • hot_rodhot_rod Posts: 11,859Member
    This piping would give you better hydraulic separation and also thermostatic protection for the boiler. The electronic control for protection probably shuts off the boiler circ until the boiler catches up?

    If the home is demanding 38,000 btu/hr. with all 3 zones calling, you only have around 20K available for DHW production, or about .65 gpm, a small lav faucet flow.

    You could also choke back he Quicksetters, from 2 gpm each. If the load is 38,000, you only need to move 3.8 gpm total at 20∆. Zone by zone heat load would show you where to set the Quicksetters.

    I'd rather the expansion tank connected at the botton connection to the TurboMax, then both circs are pumping away. Boiler pump could move down to the boiler return, closer to the PONPC, not a big deal with a wide open cast boiler.

    A reverse indirect stores very little DHW in the coils, so it behaves more like a tankless heater, you need all available BTUs to maintain tank temperature during DHW, so heating loads need to drop off.

    All zones cast iron radiators? Again not an ideal match for ∆T circulation, fast responders like fin tube work better for that logic.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited March 31
    hot_rod said:

    This piping would give you better hydraulic separation and also thermostatic protection for the boiler. The electronic control for protection probably shuts off the boiler circ until the boiler catches up?

    If the home is demanding 38,000 btu/hr. with all 3 zones calling, you only have around 20K available for DHW production, or about .65 gpm, a small lav faucet flow.

    You could also choke back he Quicksetters, from 2 gpm each. If the load is 38,000, you only need to move 3.8 gpm total at 20∆. Zone by zone heat load would show you where to set the Quicksetters.

    I'd rather the expansion tank connected at the botton connection to the TurboMax, then both circs are pumping away. Boiler pump could move down to the boiler return, closer to the PONPC, not a big deal with a wide open cast boiler.

    A reverse indirect stores very little DHW in the coils, so it behaves more like a tankless heater, you need all available BTUs to maintain tank temperature during DHW, so heating loads need to drop off.

    All zones cast iron radiators? Again not an ideal match for ∆T circulation, fast responders like fin tube work better for that logic.

    Thanks so much; yes with 58,500 dhw load plus 38K heat load we're up to near 100K simultaneous load. Though in reality max load is really maybe 58,500/2 since at most wife and I take back to showers for 15 minutes each, and really only rarely back to back. But that still puts combined loads about 70Kbtu. Yes, we definitely want to have dhw priority. Turbomax 45 first hour/continuous ratings @50k net btu are 99/75 gal respectively given rise from 40º to 120º and boiler feed temp 160, return 140.

    I see you use DOE output not 50Kbtu net for this boiler --I guess since there's no pickup factor for dhw piping.

    Quicksetters: I think they were set at the minimim of 2 gpm already, not sure they can go down lower.

    Emitters: Main floor cast iron, 17k loss, 16k gain; 2nd floor cast iron, 10k loss, 11.5k gain; basement baseboard, 11k loss, 6800k gain. the logic of having quick setters was to equalize flow when required.

    And yes control should allow us to have circ shut at 130, though the hydrostaT 3200 --approved and installed on boiler by Peerless--has its own 'circulator hold off' setting which seems to require boiler to heat to 125 before activating circ, and then shuts it if temp reaches below 115º. seems kind of low, but probably for short time periods, like Buderus pump logic. That feature may be working now, have to verify.

    The other issue with the control was that with dhw priority activated the zone valves on every dhw call...

    Exp tank: I had assumed boiler circ was pumping away from PONPC....

    And yes this was planned as a buffer/dhw combo, given the shoulder or even average winter season microloads. zone heat loss listings right above were for 10ºF OT. And as you seem to say, trying to use the 50 gallon Turbomax 45 as only for Dhw not buffer still requires the boiler btus to drive it so that may not be 'a way out' of this. My wife and I have used a 30-40k btu 50 gal standalone hwh for years never ran out of water. In retrospect a standard indirect might have been easier from the get go, but it sounds like a few hours of re-piping and some other changes might do the trick.


    Your comments are greatly appreciated. We'll be digesting all this–– we're lucky spring is upon us things are not urgent––and try to come up with a plan once the chimney liner installed this week.
  • hot_rodhot_rod Posts: 11,859Member
    for DHW, if you use a temperature lift of 40-110F
    500*1.5*70°F = 52,000 BTU/hr. So with 1.5 gpm shower heads you should be able to shower without limits. Heating zones off, of course.

    My main though is the buffer piping. Without that close large connection detail, I think the boiler and system pump may basically be in series.

    This drawing shows the concept of flow thru the tank as the heating flow rate, based on which zones are calling, change.

    So lets say the boiler pump is 6 gpm always. The zones can be anywhere from 1- 3.9 gpm.

    Under no heat condition you have 6 gpm thru the tank, great for DHW.

    With various heat zones toggling on/ off that flow splits thru the tank based on what gpm is being used in the zones.

    When piped correctly the heat zones could pull from the tank without the boiler firing, until the tank drops to the lowest usable temperature.

    If you have generously sized radiators, you may be able to pull the tank down to 140F? Lower?

    Determine what the TurboMax could supply for Dhw if it drops to 140F.

    One further improvement would be to pull the heating loads off the tank based on ODR, allowing more useable buffer. But more piping and component complexity. On milder days no need to send 160 or higher, you may sneak up on constant circulation :)

    For any or all of this to work I think you want to change the buffer tank connection a bit.

    I'd switch the ∆P circulator to the zone valves.

    Yes, watch that boiler return, no more than 10 minutes before you are running above condensing return temperatures. I think 115F return or boiler temperature is way too low for extended run times.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited March 26
    @hot_rod you said: for DHW, if you use a temperature lift of 40-110F
    500*1.5*70°F = 52,000 BTU/hr. So with 1.5 gpm shower heads you should be able to shower without limits. Heating zones off, of course.

    I assume when you speak of delivered water temp of 110, that somehow includes the calculation of the fact that the water is being heated to around 160, then mixed down to 110-112 at Turbomax then is slightly less than 110 at shower.

    "My main thought is the buffer piping. Without that close large connection detail, I think the boiler and system pump may basically be in series."
    Could that be the reason the zone valves were opening during DHW priority? The ∆P circ was 'pushing' through the return, the boiler, then the heating circ, sucking the zvs open?

    I have attached photos showing the areas of piping I think you refer to. (Note on photo showing Turbomax top, understood that the yellow vertical line showing proposed buffer location, would be replacing the existing black pipe, not the copper ones.)




    I also uploaded the pump curve of the ∆P circ (fixed circulation) to show where ours is set, sort of #1, the first setting after the lowest. Not sure what our head would be, can't be much, so don't know if flow is high enough. This week I'll be observing and logging what I can; seeing how low the boiler water temp goes when all three zones call.
  • hot_rodhot_rod Posts: 11,859Member
    Do you need to run 160F, ever? Either calculate, estimate, or use trial and error to see what SWT is required on design, or coldest, windiest condition :) The hotter you run the tank, the more energy loss and energy $$. Use to be those tanks had a minimum 1/2" fiberglass insulation. Hopefully it has been beefed up. I'd like to see 3" or more insulation on high operating temperature tank.

    Keep in mind the tank needs to be maintained year around for DHW now. I'd consider adding a water heater tank blanket when you are done for added R-value. I'd also run as low as possible in summer mode for DHW, you may be able to run 140F or lower, again trial and error or use the formula I've shown. If you can and do run the boiler below 140 set, you will need return temperature protection. if your control has a bang/ bang control for the boiler pump, that is one method. Or add a thermostatic return temperature valve.

    The circulators need to be disconnected from one another, hydraulically speaking. The oversized piping at the tank develops a hydraulic separator to allow either/ or, or both too run at various flows and not effect one another. Leave the checks in the circs for added ghost flow protection.

    With those unions I think you could modify the piping easily. I use a 2X 1-1/4 ell at the tank bottom and some 2" reducing tees to build it up. Same up top with a 2x 1/14 bell reducer close nippled to the tank, then some 2" reducing tees or fittings.

    With the boiler circ running 6 gpm, and zone circ around 3 gpm max you have 9 gpm potential at the sep. 2" pipe at that flow rate is below 1 fps, providing that low velocity zone needed for separation.

    Use the 1816 as the heating zones circulator in ∆P mode, not sure which setting, trial and error or calculate pressure drop in the zones. ∆P is for zone valved applications. With those ball valve ZVs and the circ in ∆P you should not have any ghost flow issues.

    The other circ in fixed speed, providing 6 gpm at a few feet pressure drop thru the boiler and piping. 6 gpm will give you the best output from the TurboMax in DHW mode with the boiler hp you have available.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited March 31
    I was up around 6am today monitoring the boiler during its 3 zone return-to 65º from overnight setback of 63º. The results showed me that whether the Hydrostat's circulator-hold protection is not working or the re-wiring to avoid ghost heating flow during DHW cycle disabled the feature, the boiler was clearly condensing for over an hour, and that's probably happened on a few other days. OT's the last few mornings have been about 30º. House took about 1.5 hours to warm up the air and furnishings.

    Results:
    With three zones running zone circ readings had supply temps ranging from 114, 118, 122, 4gpm 64 watts with return temps of 61-75. At its lowest Turbomax got to about 130. When two zones ran, it was 3gpm. The t-stats went off and on as did Zvs several times. Boiler temps were around 120 or lower.

    Note: The location of circulator's return temp sensor is BEFORE the heating return is joined by the buffer return which is much warmer. So the low return readings may not be accurate compared to the actual return temp if measured a few inches before the return pipe enters the boiler.

    I have immediately removed the setbacks on all three zones and will monitor again tomorrow. In answer to @hot_rod about max required supply temp, while based on the loss and emitter studies done by installer we figured that for the mod con we originally intended to install we could use 140º as the max supply temp for a design day, I believe that most heat loss calcs omit setback recovery if there is one. Even two degrees recovery on a 30º morning must add a certain percent of additional heat loss to my 38Kbtu, as does having to maintain the temperature of the Turbomax's 48 gallons. So from now on no more setbacks. I would hope that summertime we could try 140-145 hi limit temps for the DHW.

    And of course @clammy thanks much for your detailed thoughts, esp re check valves, etc.

    @hot_rod I see your constant pressure mode loop diagram shows zone valves on the supply side (fairly rare I guess) with zones in order of smallest to largest.
  • hot_rodhot_rod Posts: 11,859Member
    The ZV drawings are Tacos. I prefer ZVs on supply to assure 100% protection from ghost flow. With ZVs on returns you may still get some thermal migration up the off zones, on a single circulator multiple ZV layout.

    For DHW it is always a surface area game. If you have enough coil area you may be able to get adequate DHW dow to 120° tank temperature. I run DHW from a flat plat HX in my shop and can shower with temperatures to the HX at 110°F. 103° is a typical shower temperature, so with enough HX you could get within a few degrees from tank temperature to DHW output.

    In the HX business they call that "close approach' and 3° is possible.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited March 28
    I thought minimum tank temp was 140 for protection against bacteria?
    ...a bit less water capacity if not mixing down from 140... but our peak load is one shower or dishwasher load, not back to back....
    But no condensing risk at 120?
  • HenryHenry Posts: 914Member
    Legionella survives to 139F. We have specifically legislated minimum tank temperature at 140F and faucet temperature at a max of 120F. Therefore tank 140F, a tempering valve at 120F
  • D107D107 Posts: 1,580Member
    edited April 18
    Update. It was decided for the sake of simplicity, to repipe Turbomax to indirect function only, no buffer. Heating and DHW supply pipes were re-aligned. Check valves were added to dhw and heat returns, and also to the domestic hot water connection. So far system tests shows no more heat migration into heating lines on dhw call or into top of tank piping.

    Only issue is the Ranco 060-200 aquastat was found to be defective--the circ simply won't shut off except at 95º. Awaiting warranty replacement. Wiring was checked on aquastat, relay, hydrostat 3200+ and culprit seems to be aquastat. I'm interested to see how much savings I'll see from the old oversized 1981 WM boiler. See photos
    below.








  • gaabbeegaabbee Posts: 25Member
    So question because I am looking to do something similar. If you were to put a brazed plate hx to separate the boiler/turbomax loop and your zone loop would this make any difference?

    My thought process is the boiler maintains the temp for dhw at 120-140 in the Turbomax and the boiler water runs through one side of the hx.

    When a zone calls for heat both pumps turn on and the zone water runs through the other side of the hx taking heat off the Turbomax and boiler.

    Hope this makes sense.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,047Member
    @D107,

    Your combustion #s look good but I am a little concerned about 11.7 Co2 on gas. I would keep an eye on this although you Co is fine as well. You may not have much 'cushion" a little cat hair, dryer lint or dust could push you over the top
  • D107D107 Posts: 1,580Member
    edited April 21
    @EBEBRATT-Ed Installer's coming back next week so hopefully that can be looked at.
  • D107D107 Posts: 1,580Member
    edited April 21
    @EBEBRATT-Ed i just noticed isn't the 11.7 just a reference range? Actual co2 seems to read 6.90.

    Also in the pic before that at the top you can see a spring loaded check valve to stop dhw migration. Do you recognize the brand? I always like to gather a full list of the system components. Only says 200 WOG which is probably pressure rating and water oil gas.
  • hot_rodhot_rod Posts: 11,859Member
    Most all the valve manufacturers offer spring checks like that, looks like an Apollo, Conbraco?

    Ideally a valve installed like that, without a thermal drop, should have checks. Caleffi offers a check version of the 521, also a press tailpiece with checks.

    Also a new double union check.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited April 21
    @hot_rod If I'm understanding you correctly you're talking about two things, one, the spring check that brass cylinder in the upper left of the first photo below that may be a Apollo/Conbraco?

    Then I think you're talking the thermostatic mixing valve(?) that is also available built-in checks. Not sure which Caleffi 521 I have. On side it says 4318. Cap just says 521. According to the literature, the 'AC' or 'C' version includes the check valve. Mine includes the temp gauge. See photos. So you're saying if I had the 521C I wouldn't have needed the separate spring Conbraco check?






  • hot_rodhot_rod Posts: 11,859Member
    Correct, the Caleffi are available with or without checks.

    The check you have should work ok, no ned to add another. Is that check a low lead version? Any component that touches potable water needs to be low lead. AKA LF, which is how some model numbers start now if they are lead free brass.

    Also the T&P valve needs to have the probe into the tank. I doubt the probe is long enough to reach into the tank?

    You may also need a thermal expansion tank.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Danny ScullyDanny Scully Posts: 1,219Member
    edited April 21
    @hot_rod, why do you doubt the probe is long enough? You can see through the pipe? :wink: Also, a Turbomax doesn’t have a “tank” for the domestic side, but rather a coil.
  • D107D107 Posts: 1,580Member
    edited April 21
    @hot_rod thanks for your observations. Other photos didn't show, but there is a small expansion tank--see below photo. The check valve has no make or model# on it. They mentioned something about lead-free--have to check that out. I had never heard of this requirement.

    As for T&P valve, you're saying probe wouldn't reach long enough? Bottom of T&P--excluding probe--is about 12 inches above tank top. I'll await your answer to @Danny Scully's question.


  • Danny ScullyDanny Scully Posts: 1,219Member
    No need to wait for a response from @hot_rod @D107. The expansion tank is sized properly, the check valve is lead free, and the relief valve is installed in the right location. @EzzyT is an extremely competent contractor.
  • hot_rodhot_rod Posts: 11,859Member
    The model number usually indicates the lengthy of the probe, -8 for example. The Watts 100 series goes up to 8" in length.
    The tip of the probe needs to be into the tank to be code and manufacturer compliant. If that is the case you are all set.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    edited April 21
    The T&P is the Watts 100XL-8 M7 150psi 210º, so the probe is 8 inches long. The distance from the top of the valve to top of tank is about 15.5 inches. In page 2 the attached diagram the 'B' dimension, the overall height of the valve, with lever down, not including the thermostat element length, is 3 11/64". Add the 8 inch probe = 11 11/64 inches full valve length.

  • Danny ScullyDanny Scully Posts: 1,219Member
    Again, the Turbomax does not have a “tank” for the domestic side. As a comparison, “tankless” water heater relief valves typically don’t even have probes.
  • D107D107 Posts: 1,580Member
    edited April 21
    @Danny Scully @hot_rod Attached diagram shows the Turbomax without a T&P valve, only a Pressure relief valve which covers the 'boiler water' in the tank. We have that. So in that diagram at least they're not showing a need to protect for the 32.7 sq ft of the Turbmax 45 coil's heat transfer area.


  • Danny ScullyDanny Scully Posts: 1,219Member
    The relief valves for both the heating and domestic side are detailed in the installation manual. I’m just reassuring you @D107 that it is installed properly. You should have many years of reliability and comfort ahead of you.
  • HenryHenry Posts: 914Member
    Just don't exceed the flow rate in the manual. They will not cover the tank under warranty if the flow rate of the domestic heated water is exceeded.
  • hot_rodhot_rod Posts: 11,859Member

    The relief valves for both the heating and domestic side are detailed in the installation manual. I’m just reassuring you @D107 that it is installed properly. You should have many years of reliability and comfort ahead of you.

    Point taken that it is not a DHW tank type heater, and pressure only may be all code requires. As long as the inspector knows what he is look at :)

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • D107D107 Posts: 1,580Member
    Well thanks gentlemen for your contributions--even on this Easter Day. Turbomax manual's illustrations are not always easily legible, and their instructions at times ambiguous, but my takeaway is that the installer, characteristically, put in the T&P as an extra precaution, and that the bottom of the probe being a few inches above the tank still provides an extra margin of safety. Happy holidays to all.
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