Saskatchewan Hydronic Heat Components

Discussion in 'Maintenance and Troubleshooting' started by BatocheBob, Nov 4, 2015.

  1. BatocheBob

    BatocheBob Member

    This is sort of a continuation of my previous thread titled 'How much floor tubing' We did kinda' sort that issue out and, thanks mostly to UrthBuoy, managed to generate some heat in the zone. However after a couple of days of constant running we still cannot generate the desired warmth and appear to be maxed out on that loop. Upon closer inspection my other four zones look a bit suspect although they do seem to be generating enough heat.

    Here's the various components I am looking at with a bit of suspicion:

    My zone circulation pumps are delta P pumps (Wilo-Stratus ECO 16). From what I have recently learned I question why delta P pumps would be specified on a thermostatically controlled system? There is also some suggestion that the pumps are too small which leads me to my next point.

    The loops in this zone are 5/16 AquaPex set in Uponor QuickTrac. In the loop of greatest importance the total length, including the runup & return from the manifold, is 150' There are no fittings in this loop. Can someone please calculate the Head Loss in this loop? The other 3 loops in this zone are similar or in one case greater. I believe that the head Loss for all 4 loops combined will determine the size of pump required for that zone. The current pump supports 16' of head Loss.

    My delta T is another concern. A few people have suggested that a value of 10 - 15F is desired. In the one loop that I am most concerned about I have reduced the delta T to about 15F @ 0.4 gpm. In other loops I have checked my delta T's and they range from 20F to as high as 35F. I understand that a high delta T is usually the result of insufficient flow. One of my other concerns is that the Uponor EP manifolds have a maximum flow rate of 1.2 gpm on each port (the main manifold supports 14 gpm).

    Any suggestion and info will be appreciated. if i can provide any additional info let me know. Thanks
     
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Found the charts for 5/16"
     

    Attached Files:

  3. BatocheBob

    BatocheBob Member

    Thanks Chris. If I'm reading that chart correctly, 5/16 running a 30% glycol mix at .4 gpm results in a head loss of 4.95 per hundred. Am I correct?
    In terms of the pump do I consider the head loss for all 4 loops or just the longest loop?
    For the optimal flow I see a formula that suggests gpm=btuh/delta T*500. If I'm reading the specs I have correctly it shows that my bathroom requires 5100 btu's. I'm assuming that's 5100 btu/h. Does this sound reasonable for a 11' x 11' bathroom with a 5' x 4' window & a smaller 2' x 2' window. The bathroom has two outside walls but is weel insulated with triple glass with double gas. If so that suggests a flow of 0.7 gpm. At that rate it looks to me like my head loss would be 17.85 which exceeds the capacity of my pump. Hopefully that's not the case.
     
  4. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Thoughts.

    You use the headloss for the loop that you are concerned about. But, you're right, parallel circuits don't add in headloss. The longest would have the most headloss, which generally dictates the pump size. But flow is divided through the open circuits.

    For your area, I could see a bathroom with two outside walls, needing 5000 btu/hr. That formula is the go to for radiant and gets you in the ballpark for many things.

    Your piping diameter is too small really. Probably why I hadn't heard of it before in this country "north of the wall". The small stuff that we use is 1/2".

    There are two options - increase water temp or increase pumping power. Neither one is a great efficiency solution.

    You could also plumb in a decorative heated towel rack as an additional zone to that room?
     
  5. BatocheBob

    BatocheBob Member

    I guess I have to ask, why would a reputable heating company specify 5/16 Pex to supply 5000 btuh in a geothermal system if it is not adequate. Why would re-sizing the pump not be an efficient solution; is it because of the cost and higher power consumption?
     
  6. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    You can upsize that pump for sure. And get those btu's moving. But, now you have a grasp of how this could have been optimized better. That headloss is excessive and requires additional pumping power that one could have reduced with right-sizing materials.

    I'm not sure why 5/16" was originally spec'd. Maybe they knew a run of 150' (I can't recall your original number) was all that was required for this zone. There are tables that recommend max circuit length based on pipe diameter. And that is how they chose 5/16? The problem is that doesn't consider the heat flux and that we are dealing with 100F vs 180F water temps.
     
  7. BatocheBob

    BatocheBob Member

    You know, I believe there is something to the old adage 'good help is hard to find'. I pulled out my drawings and spec sheet that was drawn up and I think the guy who did this up was drunk or something. On the spec sheet the demand for the bathroom is 6,796 btuh but on the loop drawings the demand is 13 btuh @ .11 gpm. After everything I have worked through on my system I think I should go into the geothermal consulting business;-) I'll try going back to the design company and see what I can work out. Thanks
     
  8. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Many frustrated homeowners who come here seeking help and sanity go on to help others both here and locally. Education and understanding is the gift that keeps giving.
    Eric
     
    heatoldhome and ChrisJ like this.
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Bob:

    Lets cut that zone in half to lower the head. Add a two port manifold to what is there. One port to the bath floor and one to the new towel warmer.

    Now your pump fits.

    Mark
     
  10. BatocheBob

    BatocheBob Member

    Mark thanks for you suggestion. When Chris suggested adding a nice towel warmer I thought he was joking but now I'm thinking it is a possible option. Tell me you guys are serious about a towel warmer.

    Here's where I'm at right now. I spoke to the company who designed and built my hydronics board. Given that I have thermostatically controlled zones the guy questioned why I had Stratos ECO 16 pumps. He recommended I replace the pump in the troublesome zone with a Wilo Star S 21.

    I then spoke to the Wilo technician and he agreed that because the ECO 16 is a delta P pump with modulating circulation it was possible that the existing pump was throttling back when it encountered a high resistance. Like yourselves he questioned using such small Pex (5/16) but agreed the Star s 21 should improve the performance of the loop.

    I then went on to speak to the technician at Uponor and he was very confident that a 5/16 loop of 150' could easily be fed by even the smallest of pumps and that a ECO 16 should handle it easily. However he then went on to say that he didn't think a loop like that could supply 5000 btu/h.

    I did swap out the pump for a Star S 21 and have seen some improvement. I now have .5 gpm with a delta T of about 10F. According to my math I should be able to provide 2500 btu/h. This fits in with your suggestion Mark. I look forward to any comments. Thanks.
     
  11. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Towel warmers are a real item - and some have rated heat outputs
    http://www.myson.co.uk/products/towel_warmers.asp

    I have to backup a bit. Do you have multispeed pumps on single zoned headers? The don't have much advantage in that type of setup. I was assuming you had multizones served by each pump. If not, fixed speed circulators are fine.
     
  12. BatocheBob

    BatocheBob Member

    Chris, yes I realize now that towel warmers can be a real heat source; sorry for doubting you. My research would seem to indicate that the most you can get out of the towel warmers they sell around here would be about 900 BTU/h with 104F water. At around $2500 SRP it would hardly be worth it and besides I probably need an additional 2500+ btu's to get that room up to a temperature that would satisfy my wife. Hell she's even bellaching about cold towels but for the money it costs even she said she'd forego the towel warmer :) A hydronic baseboard might be a more cost-effective option. The other option I'm looking at is to run a hot air duct over there.

    At the present time, with the new pump having run continuously for more than 24 hrs., my floor temp in both areas is about 79F. The air temperature in the bathroom is about 19C.

    I have another little dilemma. Since I have two more loops to implement my first reaction was to switch to 1/2" Pex but I'm wondering if it is a good idea to run un-balanced manifolds and if I balance the manifold it would have to be balanced at the lowest common denominator which is a scant .5gpm. At that flow I don't think I would gain anything with 1/2" would I? Thanks.
     
  13. BatocheBob

    BatocheBob Member

    One more thing about the pumps. To try and clarify I have 4 other zones, the biggest having 7 loops. Each zone (manifold) has it's own circulating pump. These pums are delt P variable circulation pumps. I think this is what you said, multi-speed pump on a single zone header. Gotta wonder what the guy who designed the board was thinking. But unfortunately I cursed this guy and his partner so much I guess the geothermal gods struck em' both dead.
     
  14. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    No. Your circuits, on a manifold, can be a wide variety of sizes.

    Seeing as you are already venturing down the rabbit hole - https://www.taco-hvac.com/images/ahrtest/DesignCommissioningTips.pdf

    Also, you can likely put together something relatively nice out of copper as a heated towel rack.

    If you, by chance, can draw out your distribution system - we can likely sort something out for you. This would be: pump size + circuit length + piping diameter. Generally, you'd be looking at one multi-speed pump servicing that entire zone system. But, because you have primary/secondary piping you do need individual circulators for each of those zones. But if they are only 1 zone each, then they can be more cost-effective single speed pumps. I'm not asking you to replace your entire system, but it sounds like you have two "right idea" concepts (variable speed pumping and hydraulic separation) poorly combined.
     
  15. BatocheBob

    BatocheBob Member

    Chris, if I'm understanding you correctly, your saying that I can make the two remaining loops in zone 5 1/2" pex and balance the manifold at .5 gpm and still make a gain on the 1/2" loops?

    I have attached the drawing for my main floor hydronics. Ithink you already have a picture of my board. The main circulation pump on that board is a Wilo Star 21 FX (21' of head). Zone pumps are Stratos ECO 16 (delta P variable speed rated for max 16' head) except for zone 5 which is now a Star S 21. Manifold 5 is the one we are talking about. The foyer and bathroom are already set in stone. I believe the supplemental heat referred to on the diagram is the spill-over heat from the main floor hot air system. Unfortunately there is no appreciable amount of heat 'spilling' from the bedroom into the bathroom. One fundamental flaw in the design is that the entire main floor hot air is controlled by a thermostat in the living room/dining room area. This results in the bedrooms, because they are quite separate from the main area, always being below set point. That's OK by us though because we don't like the bedrooms too warm. I sure appreciate your offer and grateful for any ideas. Always glad to provide any further info if it's needed.
     

    Attached Files:

  16. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Bob,

    I am not going to do this for you. I do not need to know what went wrong.

    I think in BTUH in three manors, steam, water, and air.

    If you take the 5/16" loop and divide it you lower the head loss for the old pump or the new pump. Add two zones. Bath floor and towel warmer.

    Controls are optional.
     
  17. BatocheBob

    BatocheBob Member

    Mark,

    Sorry, I'm not sure what you are referring to but it sounds like I somehow managed to tick you off.

    As for dividing the loop in half, this loop is obviously buried in thinset and tile and unfortunately I don't have the money or the inclination to demolish my bathroom. If I can't find another option and my bathroom is going to feel like a meat locker I can at least think that like any other piece of meat I may last a bit longer;-)
     
  18. geoxne

    geoxne Active Member Forum Leader

    Bob

    As you understand by now the biggest failure here is the assumption that 75ft of 5/16" pex would provide anywhere near 5kbtu's. Bathrooms are notorious for limited installable floor space for radiant tubing. There are many ways to get more tubing and loops in the room (like running it up the wall) but that doesn't help you now.

    I am familiar with QuickTrac and it's capabilities. It does well as a thin above subfloor system when designed properly. The best I could get out of it with a 10f delta at 100f supply at .4 gpm per 150ft circuit (for reasonable head) was 15 btuh per sqft installed in the floor. With your figures that calcs out to-

    44 sqft installed in a 121 sqft room?

    660 btu/hr total output to room that requires 5,100 btu/hr? That's a huge shortfall. All the pump in the world is not going to get you there. Think about BTUh=GPMxDeltaFx500. GpmxDeltaF would have to equal 10 to satisfy load. At the extreme that would approach infinite GPM at zero DeltaF. A less extreme 10 GPM at 1 DeltaF still rediculous. You would be wasting time and $ on any further pump changes.

    Your latest figures .5 gpm x 10f delta x 500 gets you 2,500 btu/hr. where are those btu's going? Is your floor insulated underneath? How much temperature are you losing between the manifold and the floor?

    You need to find a supplemental heat source for your bath hydronic or otherwise.
     
    Last edited: Nov 8, 2015
  19. heatoldhome

    heatoldhome Geo Student Forum Leader

    Radiant walls/ceilings could be added.
    Also there is low temp baseboards with small fans in them.

    Towel rack made from copper pipe and painted could be a option as someone posted.
     
  20. BatocheBob

    BatocheBob Member

    Thanks for the latest replies geoxne & Geo Student. Unfortunately most of this project is already completed and fell short because of what looks to be a poor design. When I look back at my drawings the square footage for the bathroom is shown as 65% of what it actually is. The whole issue revolves around the specification for 5/16 pex. Uponor states that you can have a maximum 250' loop using 5/16 and they tell me that the smallest of any circulating pump will be sufficient. They did admit that the most they would expect to get from a QuickTrac system is 13 btu/sq.ft Their pressure loss tables state that 100' of 5/16 pex running 30% glycol at 100F at .5gpm has a pressure loss of 8.43/100'. I'm assuming this translates to head loss so for 250' you're looking at 21 feet of head loss f I'm interpreting this correctly. I don't understand how you could run a loop like this with the "smallest of circulating pumps". Take away 50' for run-in and the remaining pipe is lots to cover a 10' x 10' room. At the 15 btu/h you referenced that's 1500 btu/h for a 100 sq. ft. room; that's got to be one hell of a well insulated room.

    To get back to my room, at it's best the input water at the manifold is 104F and about 95 at the return. I have no way of telling what the water temperature is when it reaches the floor except to say the floor temperature is 79F. There is insulation in the joists under the bathroom and I will be insulating the lead-in tubing from the manifold. Even though the basement is heated to 22F I appreciate that the tubing could be giving up heat before it reaches the floor. We do agree I would seem to be getting 2500 btu/hr and I'm assuming that most of it is going into the bathroom which might explain why the room temperature is around 66F; not exactly the meat locker I alluded to earlier but not enough to keep my wife warm. remember this is a room that is supposed to require 5,000 btu/hr. or more by some accounts.

    If anyone wants to do their own takeoff the room is 11' x 12'. Two walls are exterior insulated with 4" of WallTite spray foam. There is an 8' ceiling with a conditioned space above. The space below the floor is also conditioned. There is a 4' x 5' fixed pane window triple glazed with argon gas between all panes. There is another 2' x 2' awning type window also triple pane, double gas. This bathroom is accessed from the heated bedroom by a 3' door so I would expect there is a bit of spill over heat but not much. Turn off the floor heat and the room gets pretty cool (I should measure that).

    Bottom line here is I appreciate every ones comments and suggestions and it has definitely contributed to my knowledge base and look out if I ever build another house (70 years old and the wife I got there's not much chance of that) ;-)
     

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