Predictika · HVAC system design checks

An AI sales agent's VRF system design, checked before it goes out

An AI sales agent prepares a proposal for a building that needs a VRF air-conditioning system: which outdoor unit, how many indoor units and how much indoor capacity, and how long and how high the refrigerant piping runs. Before the design goes out, the agent sends it to Predictika, which checks it against a declarative model of the published catalogue and returns a verdict, every reason and the figures it computed.

Scope: Mitsubishi Heavy Industries KXZ VRF systems (FDCB-KXZE1, 22.4 to 100 kW): outdoor unit model, indoor connection ratio, number of indoor units, refrigerant piping limits, operating range and signal wiring. See everything this validator covers

This validator models system designs as published in the MHI KXZ VRF catalogue (2023 Tropical Usage Model, R410A, document 23KX04E), not just the scenarios shown below.

  • Outdoor units — the 14 published models from 22.4 kW (8 HP) to 100 kW (36 HP), each with its nominal cooling capacity and the maximum number of indoor units that can be connected (22 to 80).
  • Connection — the total indoor capacity must be 80 to 130 percent of the outdoor unit's nominal cooling capacity, and the number of indoor units may not exceed the model's limit.
  • Piping and site — total piping up to 1,000 m, furthest indoor unit 160 m, first branch 130 m, first branch to furthest indoor unit 90 m, branch lengths within 40 m of each other, 18 m between indoor units, outdoor unit up to 50 m above (70 m shown) or 40 m below the indoor units, outdoor design temperatures of -15 to 52 degrees C for cooling and down to -20 degrees C for heating, no loop wiring, and the stated outdoor capacity must match the catalogue.

Any KXZ system design that touches these rules is in scope — not only the scenarios pictured here. Not covered: prices (the catalogue publishes none), indoor unit selection and controllers, other MHI series, refrigerant charge and pipe diameters, and the oil-equalizing pipe lengths. Two published values are unclear and are sent to a person: the 70 m height shown beside 50 m, and an 85 m footnote beside the 90 m branch run.

The AI sales agentBuilds the system design from the conversation and says it is ready.
Predictika validatorChecks every rule at once and returns the verdict, each finding, and the computed figures.

6 scenarios in 3 groups · each group runs from the agent’s first attempt to the outcome · click one to switch

What the agent proposes

The AI sales agent says

Illustrative agent statement. The validator receives the structured request below.

Proposing agent: AI sales agent (scripted)

Before sending, the agent must call Recorded run

Predictika validator


      

        
        
        
      

      
Waiting for the call.

      
    

  

  
  

    
Where rules-based CPQ gets it wrong
Click to expand
    
Our assessment of what a typical rules-based CPQ (product rules, price rules and validation rules, as in Salesforce CPQ) does with the same cases. It is a judgment about effort and reliability, not a claim that nothing can be built.

    
What the validator caughtTypical rules-based CPQPredictika
A connection ratio that depends on the outdoor unitOnly with care
Each outdoor model has its own capacity, so a ratio rule has to look up the model and compare the indoor total with 80 and 130 percent of it.		The limits are computed from the chosen model and compared with the indoor total on every call.
A maximum number of indoor units that differs by modelOnly with care
A rule per model can cap the count, but it must be kept in step with the catalogue as models are added.		The model's limit is looked up and compared with the number of indoor units together with every other rule.
Several piping limits that interact (total, furthest, branch, height)Only with workarounds
Each limit is a separate field check, often on a different screen, and the one that fails depends on the building.		All eight piping and height limits are checked together on every call and every failure is reported.
Published values that are unclear (70 m versus 50 m, 85 m versus 90 m)Only with workarounds
A hard rule either blocks a design that may be fine or lets through one that is not; the ambiguity rarely reaches a person.		Values between the two figures are neither blocked nor passed; they are routed to a person with the reason.
Every problem returned in one answerOnly with workarounds
Rules tend to fire as the design is saved or a step is completed, so a rep often fixes one error and meets the next.		All findings come back together, whatever order the choices arrived in.

  

  

    
What this validator catches: findings from its test cases
Click to expand
    
Every rule is checked on every call, in any order the choices arrive; one problem never hides another. Blocking findings stop the quote; approval findings need a person to sign off; everything else is computed.

    
1The indoor units total 44,799 W but the outdoor unit needs at least 44,800 W (80 percent connection).
2The indoor units total 72,801 W but the outdoor unit allows at most 72,800 W (130 percent connection).
323 indoor units are connected but this outdoor unit allows 22.
481 indoor units are connected but this outdoor unit allows 80.
5The total piping length is 1,001 m; the catalogue allows 1,000 m.
6The furthest indoor unit is 161 m away; the catalogue allows 160 m.
7The pipe run to the first branch is 131 m; the catalogue allows 130 m.
8The catalogue allows 90 m from the first branch to the furthest indoor unit but its footnote mentions MAX 85 m; the run is 86 m, so a person should confirm it.
9The catalogue allows 90 m from the first branch to the furthest indoor unit but its footnote mentions MAX 85 m; the run is 90 m, so a person should confirm it.
10The run from the first branch to the furthest indoor unit is 91 m; the catalogue allows 90 m.
11The longest and shortest indoor-unit piping from the first branch differ by 41 m; the catalogue requires 40 m or less.
12The catalogue shows 50 m with an arrow to 70 m for an outdoor unit above the indoor units and does not state the conditions for 70 m; the height is 51 m, so a person should confirm it.
13The catalogue shows 50 m with an arrow to 70 m for an outdoor unit above the indoor units and does not state the conditions for 70 m; the height is 70 m, so a person should confirm it.
14The outdoor unit is 71 m above the indoor units; the catalogue shows 70 m at most.
15The outdoor unit is 41 m below the indoor units; the catalogue allows 40 m.
16The height difference between indoor units is 19 m; the catalogue allows 18 m.
17The outdoor design temperature for cooling is 53 degrees C; the catalogue range is -15 to 52 degrees C.
18The outdoor design temperature for cooling is -16 degrees C; the catalogue range is -15 to 52 degrees C.
19The outdoor design temperature for heating is -21 degrees C; the catalogue range starts at -20 degrees C.
20The signal wiring forms a loop; the catalogue prohibits loop wiring.

  

  

    
Scenarios and results
Click to expand
    
The recorded result of the validator for each scenario on this page: the request the AI agent sent, the verdict, and every finding, in the order they appear above.

    
1. Indoor units: 56 kW outdoor unit with 50 indoor units

    
The agent's request. Please design a KXZ VRF system around the FDCB560KXZE1 (56.0 kW) outdoor unit with 50 indoor units totalling 50,000 W of cooling capacity. The piping is 300 m in total, with the furthest indoor unit 100 m away, 60 m to the first branch and 50 m from the first branch to the furthest indoor unit. The outdoor unit is 15 m above the indoor units. The design states an outdoor capacity of 56,000 W. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Too many indoor units for the outdoor unit. 50 indoor units are connected but this outdoor unit allows 48.
    • 
    

    
2. Indoor units: The agent resubmits after fixing the errors

    
The agent's request. Please design a KXZ VRF system around the FDCB560KXZE1 (56.0 kW) outdoor unit with 44 indoor units totalling 50,000 W of cooling capacity. The piping is 300 m in total, with the furthest indoor unit 100 m away, 60 m to the first branch and 50 m from the first branch to the furthest indoor unit. The outdoor unit is 15 m above the indoor units. The design states an outdoor capacity of 56,000 W. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • System summary. Outdoor unit nominal cooling 56,000 W, up to 48 indoor units; the indoor units total 50,000 W, allowed 44,800 to 72,800 W (80 to 130 percent).
    • 
    

    
3. Piping runs: 50 kW outdoor unit with long piping runs

    
The agent's request. Please design a KXZ VRF system around the FDCB500KXZE1 (50.0 kW) outdoor unit with 20 indoor units totalling 50,000 W of cooling capacity. The piping is 300 m in total, with the furthest indoor unit 190 m away, 140 m to the first branch and 80 m from the first branch to the furthest indoor unit. The outdoor unit is 10 m above the indoor units. The design states an outdoor capacity of 50,000 W. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Furthest indoor unit beyond 160 m. The furthest indoor unit is 190 m away; the catalogue allows 160 m.
    • 
      
  • Run to the first branch above 130 m. The pipe run to the first branch is 140 m; the catalogue allows 130 m.
    • 
    

    
4. Piping runs: The agent resubmits after fixing the errors

    
The agent's request. Please design a KXZ VRF system around the FDCB500KXZE1 (50.0 kW) outdoor unit with 20 indoor units totalling 50,000 W of cooling capacity. The piping is 300 m in total, with the furthest indoor unit 150 m away, 120 m to the first branch and 80 m from the first branch to the furthest indoor unit. The outdoor unit is 10 m above the indoor units. The design states an outdoor capacity of 50,000 W. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • System summary. Outdoor unit nominal cooling 50,000 W, up to 43 indoor units; the indoor units total 50,000 W, allowed 40,000 to 65,000 W (80 to 130 percent).
    • 
    

    
5. Unclear catalogue values: 67 kW outdoor unit 60 m above the indoor units

    
The agent's request. Please design a KXZ VRF system around the FDCB670KXZE1 (67.0 kW) outdoor unit with 30 indoor units totalling 67,000 W of cooling capacity. The piping is 500 m in total, with the furthest indoor unit 100 m away, 60 m to the first branch and 88 m from the first branch to the furthest indoor unit. The outdoor unit is 60 m above the indoor units. The design states an outdoor capacity of 67,000 W. It is ready to send.

    
Verdict: Needs approval.

    
    
      
  • Outdoor unit 50 to 70 m above: conditions to confirm. The catalogue shows 50 m with an arrow to 70 m for an outdoor unit above the indoor units and does not state the conditions for 70 m; the height is 60 m, so a person should confirm it.
    • 
      
  • First branch to furthest indoor unit above 85 m: footnote to confirm. The catalogue allows 90 m from the first branch to the furthest indoor unit but its footnote mentions MAX 85 m; the run is 88 m, so a person should confirm it.
    • 
      
  • System summary. Outdoor unit nominal cooling 67,000 W, up to 58 indoor units; the indoor units total 67,000 W, allowed 53,600 to 87,100 W (80 to 130 percent).
    • 
    

    
6. Unclear catalogue values: The agent resubmits after fixing the errors

    
The agent's request. Please design a KXZ VRF system around the FDCB670KXZE1 (67.0 kW) outdoor unit with 30 indoor units totalling 67,000 W of cooling capacity. The piping is 500 m in total, with the furthest indoor unit 100 m away, 60 m to the first branch and 80 m from the first branch to the furthest indoor unit. The outdoor unit is 45 m above the indoor units. The design states an outdoor capacity of 67,000 W. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • System summary. Outdoor unit nominal cooling 67,000 W, up to 58 indoor units; the indoor units total 67,000 W, allowed 53,600 to 87,100 W (80 to 130 percent).
    • 
    

  

  

    
Narration transcript
Click to expand
    
The text of the narrated walkthrough, step by step.

    
    
      
  1. Welcome to a demo of Predictika's Validator. An AI sales agent prepares a proposal for a building that needs a VRF air-conditioning system: which outdoor unit, how many indoor units and how much indoor capacity, how long and how high the refrigerant piping runs. Before the design goes out, the agent sends it to Predictika, which checks it against a declarative model of the published catalogue and returns a verdict, every reason and the figures it computed.
    2. 
      
  2. I will start with the first request by the agent.
    3. 
      
  3. The agent says. Please design a KXZ VRF system around the FDCB500KXZE1 (50.0 kW) outdoor unit with 20 indoor units totalling 50,000 W of cooling capacity. The piping is 300 m in total, with the furthest indoor unit 190 m away, 140 m to the first branch and 80 m from the first branch to the furthest indoor unit. The rest of the request is on screen. The design states an outdoor capacity of 50,000 W.
    4. 
      
  4. Before it goes out, the agent calls the validator.
    5. 
      
  5. Blocked, with two findings, all in one answer. The furthest indoor unit is 190 m away; the catalogue allows 160 m. The pipe run to the first branch is 140 m; the catalogue allows 130 m.
    6. 
      
  6. The validator returned two blocking findings in one answer. A check that reads one field at a time would pass most of this; it shows only when the choices in the quote are checked against each other.
    7. 
      
  7. What this shows: for a maximum number of indoor units that differs by model, a rules-based CPQ is error-prone for this.
    8. 
      
  8. Now the agent resubmits.
    9. 
      
  9. The corrected request. It changes the furthest indoor unit to 150 m and the to the first branch to 120 m.
    10. 
      
  10. It calls the validator again.
    11. 
      
  11. This time the validator clears it.
    12. 
      
  12. Both earlier findings are cleared.
    13. 
      
  13. Two problems caught in one call, fixed in one pass, and a clean quote. That is the value of Predictika's validator: catching mistakes before they reach the customer. Now you can try the other scenarios yourself.
    14.