⚡ Quick Answer (Read This First)
If your water is not hot enough, it’s usually caused by:
Not enough heating time
Hot water being used too quickly
Tank size too small for your household
Using a too large rain shower that has very high flow rate
👉 In many homes, the real issue is insufficient tank capacity.
🔍 Quick Self-Check (2 Minutes)
🔍 Quick Self-Check (2 Minutes)
✅ Step 1: Did You Wait Long Enough?
Storage heaters need 20–30 minutes to heat depending on capacity
If just turned on → water will be lukewarm
For the recommended heating times, please refer to the table below for the estimated time required for the water heater to be fully heated:
Model | Volume of Tank (Litres) | Time To Heat (Minutes) |
JSH 25 | 25 | 20 |
JSH 35 | 35 | 30 |
JSH 38 | 38 | 35 |
JSH 50 | 50 | 45 |
JSH 56 | 56 | 50 |
JSH 68 | 68 | 60 |
JSH 91 | 91 | 60 |
JSV 25 | 25 | 20 |
JSV 35 | 35 | 30 |
JSV 50 | 50 | 45 |
✅ Step 2: Is Someone Else Using Hot Water?
Storage heaters share hot water across all outlets
Shower + kitchen + multiple users = faster depletion
👉 Water may start hot, then turn cold
🔥 Most Common Reasons
🔥 Most Common Reasons
1. ⏱ Insufficient Heating Time
Heater didn’t fully heat the tank yet
👉 Very common in morning rush
2. 👨👩👧👦 High Household Usage
Multiple showers back-to-back
Kitchen + bathroom usage together
Multiple connections where 1 Heater is connected to 2 bathrooms
👉 Tank empties faster than it reheats
3. 📐 Tank Capacity Too Small (Most Overlooked)
This is the #1 reason in Singapore homes.
Household Type | Recommended Tank Size |
1–2 persons | 25–38L |
2–3 persons | 38–56L |
3–5 persons | 50–91L |
Large family | 91L+ |
👉 If your tank is too small → water will never feel hot enough during usage
4. 🚿Shower Head Size is too large (Most Common Reason)
Many customers install:
❌ Large rain shower heads
❌ High-flow mixers
But use:
❌ Small tank heaters (e.g. 25L)
👉 Result:
Hot water runs out VERY FAST
Water feels lukewarm even though heater is working properly
Why This Happens
High-flow shower heads:
Use more litres per minute
Drain hot water faster than heater can supply
👉 Storage heaters are capacity-based, not continuous heating
Real Example
25L heater + rain shower
→ hot water may last only a few minutesSame 25L heater + low-flow shower
→ hot water lasts significantly longer
✅ How to Fix It
Option 1: Change Shower Head
Use low-flow or standard shower head
Reduces water usage → hotter & longer showers
Option 2: Upgrade Heater Size (Best Solution)
Match heater capacity to your shower system
5.🌡 Thermostat Setting Too Low (Only for JSV models)
JOVEN Vertical Storage Heaters (JSV models) are the only storage heaters that comes with an adjustable temperature knob and may be set too low for comfort
To ensure that the Heater is in optimum performance, we recommend to set your heater temperature knob to the maximum
🧠 Important Insight (Most Customers Miss This)
Storage heaters don’t continuously heat during usage.
👉 Once hot water is used up:
Cold water enters tank
Temperature drops quickly
💡 That’s why:
Bigger tank = more consistent hot water
🚀 When You Should Consider Upgrading
Upgrade your heater to the latest JSH or JSV models or consider a larger volume if:
Water turns from Hot to cold during a shower
Multiple users cannot shower consecutively
You always need to wait between showers
Current tank is 25L for rain shower
💡 Why Upgrade to a Bigger JOVEN Heater?
💡 Why Upgrade to a Bigger JOVEN Heater?
✅ Supports Rain Showers Properly
Stable temperature even at high flow
✅ Longer Shower Time
No sudden cold water
✅ Better User Experience
Consistent heat
✅ Stainless Steel Advantage
No anode rod maintenance
Cleaner water
Longer lifespan
🚨Capacity Size of Heater Recommendations
🚨Capacity Size of Heater Recommendations
Capacity | Normal Shower | Rain Shower |
25 Litres | 1 Sink OR 1 Normal Shower | Not Recommended |
35 Litres | 1 Normal Shower AND 1 Sink | 1 Rain Shower 6" (15cm) |
38 Litres | 1 Normal Shower AND 1 Sink | 1 Rain Shower 6" (15cm) |
50 Litres | 2 Normal Showers |
|
56 Litres | 2 Normal Showers |
|
68 Litres | 1 Long Bath OR 3 Normal Showers |
|
91 Litres | 1 Long Bath AND 1 Normal Shower |
|
👨🔧 When to Book Servicing
Book service if:
Water is never hot
Heating is inconsistent
Issue started suddenly
Do take note of these service conditions before requesting an appointment:
Check if your heater has a valid warranty otherwise a prepayment transport fee is chargeable.
If we found any external electrical faults, no repairs will be done and there will be a diagnostic fee of $70/$85 (depending on area). We recommend you to approach a certified Licensed Electrical Worker (LEW) to check on your external wiring before contacting us to arrange for an appointment.
📅 Need Help Choosing the Right Setup?
To recommend properly, we need:
Tank size
Shower type (rain / handheld)
👉 We can recommend the correct heater + shower combination
❓ Frequently Asked Questions
Why my rain shower is not hot enough?
👉 Your heater may be too small for the flow rate
Can I just increase temperature?
👉 No. For all our JSH horizontal models, the thermostat temperature is fixed. For our vertical JSV models, the thermostat is adjustable. However, we recommend you to keep the settings at maximum for optimum heating. Flow rate is the main issue
What’s better: change shower or heater?
👉
Budget fix → change shower head
Best solution → upgrade heater