KEEPING WATER TEMP LOW AND EFFICIENCY HIGH

Transcription

1 RADIANT HEATING DESIGN RADIANT HEATING DESIGN KEEPING WATER TEMP LOW AND EFFICIENCY HIGH

2 RADIANT BENEFIT

3 RADIANT BENEFIT Comfort,low water temps, energy efficiency

4 RADIANT BENEFIT General Heat Transfer Info Three methods of heat transfer Conduction, Radiation and Convection Radiant energy travels through space without giving up its energy Heats objects and reduces body heat loss Comfort = Target MRT (Mean Radiant Temperature) Ideal Heating Curve Forced Air Radiant Floor Radiant Ceiling

5 RADIANT BENEFIT General Heat Transfer Info Water is capable of carrying substantially more energy as compared to air System efficiency = Efficient appliance + Efficient Distribution System Radiant Systems, perfect match to low temp sources Large Volume Spaces has huge energy saving potential Air Handler / Convective Radiant Floor

6 CONTRACTOR S ROLE First Rule.know whatyour customer wants! Your job: Have enough knowledge to provide a system that meets the customers expectations Most dissatisfied customers didn t get what they asked for Poor installation, cutting corners Not communicating system function and limitations Over sold performance or efficiency

7 DESIGN FUNDAMENTALS

8 STANDARD DESIGN PROCESS Key Design Steps 1. Heat Loss 2. Construction Methods 3. Zoning & Use Ptt Patterns 4. Manifold Considerations 5. Loop Layout and Performance 6. Supply & Return Considerations 7. Pump Sizing 8. Water Temperature Control 9. Heat Source Considerations 10. Filling and Purging 11. Balancing the Manifold

9 SYSTEM DESIGN CONSIDERATIONS

10 SYSTEM DESIGN CONSIDERATIONS 1. Building Room By Room Heat Loss BTU s/sq.ft Construction Method Floor Covering Tube Spacing Water Temp 3. Heat Pump Requirements BTUH Net Output Water Temp Flow (GPM) Head (ft.hd) 2. Distribution System Manifolds Loop Lengths Zoning Mixing Strategy Pump Size

11 1. BUILDING

12 BUILDING Heat Loss First thing first! Indoor vs Outdoor Heat goes to cold Nature wants equilibrium Heat travels path of least resistance Use insulation to direct path of heat transfer

13 BUILDING Insulation Guidelines for Radiant

14 BUILDING Insulation Edge Insulation Edge insulation covers the vertical area of the slab Eliminate i side losses or break conductivity i between a block wall, foundation wall or footing. If only edge insulation is used: Go vertically down past the frost line. Soil beneath the slab should be dry and water table not present. NOTE: Always follow local codes

15 BUILDING Insulation Perimeter Insulation 4 feet in horizontally around the perimeter of the heated area Eliminates migration of heat to cooler soil directly adjacent to the slab. Need to also have the edge insulated NOTE: Always follow local codes

16 BUILDING Insulation UnderSlab Insulation Installed horizontally underneath the whole heated area. Consider Under Slab Insulation if you have; Need for fast response High water table or highly conductive soil Thick floorcovering covering. If soil underneath is dry and sandy, the under slab area can be left un insulated to help build a heat sink that will maintain even temperatures. NOTE: Keep in mind that creating a heat sink requires a lot of energy in the start up phase to saturate the slab. Always follow local codes

17 BUILDING Heat Loss Do an accurate Room By Room Heat Loss Heat Lossfor Radiant is always in BTU s/sq s/sq.ft. heat intensity Once required heat intensity (BTU/sq.ft.) is known, surface temperature is establish.

18 BUILDING Floor Surface Temperature Approximation Radiant Floor Example: Room setpoint 68 o F at 20 Btu/sq.ft = 68 + (20 2) 10 = 78 F Radiant Ceiling Example: Room setpoint 68 o F at 20 Btu/sq.ft /q = 68 + (20 1.3) 15.4 = 83.4 F Room 68 o F Surface 78 o F 20 Btu/sq.ft NOTE: Surface temperature needs to be the same independent of construction ti method

19 CONSTRUCTION METHODS

20 CONSTRUCTION METHODS General Heat Transfer Info Three methods of heat transfer Conduction, Radiation and Convection Which is most efficient? Physics it s not just a good idea.it s a law!! What determines water temperature? BTU s/sq.ft Floor Covering, LESS R VALUE IS BETTER!!! Construction method Tube Spacing Consider potential water temp limits before deciding on an installation method.

21 CONSTRUCTION METHODS Sample Floor and Water Temperature Chart

22 CONSTRUCTION METHODS Sample Floor and Water Temperature Chart

23 CONSTRUCTION METHODS Slab on or below grade

24 CONSTRUCTION METHODS Slab on or below grade

25 CONSTRUCTION METHODS Slab on decking

26 CONSTRUCTION METHODS Slab on suspended structural slab

27 CONSTRUCTION METHODS Floor and Water Temperature Profile Slab 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. 80 o F 100 o F INSULATION

28 CONSTRUCTION METHODS Gypsum Underlayment

29 CONSTRUCTION METHODS Floor and Water Temperature Profile Gypsum Underlayment 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. 100 o F 120 o F INSULATION

30 CONSTRUCTION METHODS Suspended From Below With Aluminum Plates

31 CONSTRUCTION METHODS Aluminum Plates On Top Of Subfloor with 1 x 4 Sleepers with1x4sleepers

32 CONSTRUCTION METHODS Floor and Water Temperature Profile C Fin Heat Emission Plates 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. INSULATION 120 o F 140 o F

33 CONSTRUCTION METHODS Floor and Water Temperature Profile Omega AluminumHeat Emission Plates 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. INSULATION 140 o F 160 o F

34 CONSTRUCTION METHODS Floor and Water Temperature Profile Joist Heating, Tubing Suspended 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. 170 o F 190 o F INSULATION

35 CONSTRUCTION METHODS Floor and Water Temperature Profile Joist Heating, Staple Up 88 o F 75 o F 68 o F Floor Temperature Profile Wt Water Temp. 160 o F 180 o F INSULATION

36 CONSTRUCTION METHODS 1. Building Summary Do an accurate Room By Room R Heat Loss Keep BTU s/sq.ft. as low as possible Keep floor covering R Value low High mass systems require lower water temp. Use heat emission plates when mass is not available

37 2. DISTRIBUTION SYSTEM

38 MANIFOLD CONSIDERATIONS

39 MANIFOLD CONSIDERATIONS Manifold Function Centraldistribution point for loops serving specific area. Controls flow to meet heat demand for each loop. Allows for individual room zoning or zone by manifold. Before finalizing manifold location. Consider; Zoning Use patterns Floor coverings Construction method Wt Water temp requirement

40 MANIFOLD CONSIDERATIONS Manifold Location Locate manifold within reach of the rooms to be served staying within the recommended loop lengths. Too long loops requires a large pump and may not meet heat requirements of the room or zone. Typically mounted above heated floor for easier purging Can be mounted below feeding upward Hide manifold in a closet or behind a door. Ui Using a manifold cabinet can dress up the location. Never mount a manifold on an outside wall.

41 MANIFOLD CONSIDERATIONS Manifold Location

42 MANIFOLD CONSIDERATIONS Manifold Location

43 MANIFOLD CONSIDERATIONS Manifold Location

44 LOOP LAYOUT & PERFORMANCE

45 LOOP LAYOUT & PERFORMANCE Planning Tubing Layout Consider: Heat tloss Zoning Construction Methods Floor Coverings Use Patterns

46 LOOP LAYOUT & PERFORMANCE Tubing Layout Considerations Single Wall Serpentine Double Wall Serpentine Two Loop Vertical

47 LOOP LAYOUT & PERFORMANCE Tubing Layout Considerations Double Wall Serpentine Double Wall Serpentine Horizontal

48 LOOP LAYOUT & PERFORMANCE Tubing Layout Considerations Counter Flow Spiral Counter Flow Serpentine

49 LOOP LAYOUT & PERFORMANCE Loop Lengths Loop length, spacing and layout pattern is designed to meet the heating and comfort needs of the occupants at design condition Mechanical equipment to be sized to support design needs. Changing ga loop s length, spacing or pattern may adversely impact on the performance Use below recommendations asa a guideline General Loop Length Guidelines Tube Size Recommended Maximum 3/8" Nom. 200 feet 250 feet 1/2" Nom. 300 feet 350 feet 5/8" Nom. 350 feet 500 feet 3/4" Nom. 450 feet 600 feet 1" Nom. 500 feet 750 feet

50 LOOP LAYOUT & PERFORMANCE Tube Spacing Use below recommendations as a guideline Spacing guidelines is focused on meeting heat loss as well as occupant comfort General Loop Length Guidelines Spacing shown below is only a guideline. In many cases, the tube spacing in front of windows will be tighter to accommodate the higher h heat loss while the rest of the room will remain at normal spacing. Construction Method Recommended Maximum Embedded In Slab 6 12" 12" Poured Underlayment 6 12" 12" Heat Transfer Plates Above subfloor 6 12" 12" Between Joist 8" 8"

51 WATER TEMPERATURE CONTROL

52 WATER TEMPERATURE CONTROL Water Temperature Control Equipment A mixing, diverting or injection device can be used to mix the correct water temperature Consider Outdoor Reset

53 WATER TEMPERATURE CONTROL Mixing by the numbers, Mixing Valve Primary Radiant Floor 180 o F Supply 130 o F Supply 100,000 BTUH 20 o F Delta T 10 gpm 1 Valve 30,000 BTUH 10 o F Delta T 6 gpm 1 ¼ o F Return Mixing 120 o F Return 30,000 BTUH 60 o F Delta T 1.0 gpm

54 WATER TEMPERATURE CONTROL 3 Way Mixing Valves

55 WATER TEMPERATURE CONTROL 4 Way Mixing Valves

56 WATER TEMPERATURE CONTROL 3 Way Thermostatic Tempering Mixing Valves

57 WATER TEMPERATURE CONTROL Mixing by the numbers, Injection Pump Primary Radiant Floor 180 o F Supply 130 o F Supply 100,000 BTUH 20 o F Delta T 10 gpm ½ to ¾ 30,000 BTUH 10 o F Delta T 6 gpm 1 ¼ o F Return Mixing 120 o F Return 30,000 BTUH 60 o F Delta T 1.0 gpm

58 WATER TEMPERATURE CONTROL Injection Pump Mixing

59 PUMP SIZING Mr PEX Mr PEX SYSTEMS

60 PUMP SIZING Sizing Considerations The pump (circulator) is essentially the heart of the system Design to: Deliver the required flow (gpm) to all manifolds Overcoming the pressure drop (ft/hd) If under sized: May not deliver the required heat If over sized: Velocity may be too high Could create noise or even Could erode the pipe and equipment Possibly leading to premature failure

61 PUMP SIZING Sizing Considerations Net Heat Loss Determine Target Delta T Find the flow (gpm) Find the pressure drop (ft/hd) Once GPM and ft/hd are known, look at the performance curve

62 PUMP SIZING Calculating GPM Start with BTUH for the area served by pump Use appropriate Target Delta T (ΔT) To find GPM use below formula: BTUH / Target tdlt Delta T / 500 (8.33 * 60) = GPM Weight of Water per Gallon 8.33 lbs 60 minutes per hour Example: 5000 BTUH / 10 ΔT / 500 = 1 GPM 5000 BTUH / 20 ΔT / 500 = 0.5 GPM OR

63 PUMP SIZING Pressure Drop (Feet of Head, ft/hd) Resistance of flow through pipes and equipment Resistance is not a linear curve If pushing 1 gpm creates 2 ft/hd, then, Doubling the flow to 2 gpm moves the pressure drop to 8 ft/hd. A small change in flow, have a big impact on the pressure drop. Use the correct Cv chart to figure pressure drop through valves etc

64 PUMP SIZING System Pressure Drop Example NOTE: You add ALL the GPM of all the loops but only add the highest pressure drop radiant loop plus all the NOTE: You add ALL the GPM of all the loops, but only add the highest pressure drop radiant loop, plus all the piping and associated equipment.

65 PUMP SIZING Pump Curves If we select 7 ft/hd f/hdas an example, all pumps will find the 7 ft/hd spot on its curve and deliver it s flow (gpm) Pump A is simply too small (dead heading) Pump B will deliver a little over 2 gpm Pump C will deliver about 7.5 gpm Pump D will deliver a little over 55gpm 5.5

66 PUMP SIZING Location Pumping Away Place pump immediately downstream from the expansion tank or point of no pressure change Make up water should be as near as possible to the expansion tank or point of no pressure change

67 PUMP SIZING Differential Pressure By Pass Valve Avoids dead heading a circulator Used to ensure correct flow or pressure under all operating conditions. Also a good idea when a single circulator is serving zone valves or actuators. Avoids over pumping when only one or two circuits are open Allows excess flow and pressure to by pass the system Allowing only required flow to the system Or.consider a variable speed system pump

68 DESIGN TOOL

69 DESIGN TOOL Let s look at the new LoopCAD

70 3. HEAT PUMP REQUIREMENTS

71 HEAT PUMP REQUIREMENTS Key Design Elements BTUH Net Output Water Temp Flow (GPM) Head (ft.hd)

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