I’m working on optimizing my underfloor heating system. I have a 10kW system running at 35°C, but I’d like to increase the dT from 5°C to 15°C for better efficiency.
The piping from the buffer tank to the underfloor manifold is 10m of 17mm plastic(inside). The pipe from the heat pump to buffer tank is 28mm copper.
I’m also in the market for a new smart water pump that can handle constant temperature, constant dT, and volume flow optimization.
Specifically, I’m wondering if anyone has experience with Grundfos /Wilo Strato Maxo or similar smart pumps in this kind of setup.
Any advice on increasing the dT and specific pump model recommendations would be greatly appreciated!
Basic control functions for Stratos MAXO-Z
Depending on the application, basic control functions are available.
The control functions can be selected with the setting assistant:
• Differential pressure Δp-c
• Differential pressure ∆p-v
Index circuit ∆p-c
• Dynamic Adapt plus (factory setting of single and twin-head pump)
• Volume flow constant (Q-const.)
• Multi-Flow Adaptation
• Temperature constant (T-const.) (factory setting for drinking water pump)
• Differential temperature (∆T-const.)
• Speed constant (n-const.)
• PID control
Why do you think your system will be more efficient at a higher dT? Higher dT also means higher required flow temperature - you’d have to run at 40°C instead of 35°C to get the same average emitter temperature (=heat output) at dT 15 compared to dt5. You certainly can gain by optimizing dT, but mostly through reduced pump power - see my post here. Is there anything that would bring better efficiency that I’m overlooking?
it’s impossible to transport 5kW using a 17mm inner diameter pipe due to enormous hydraulic losses at a 5K dT. This is why the floor isn’t heating up.
A maximum of 2kW could be transported by the 17mm pipe under these conditions to have a reasonable hydraulic loss, which is suitable for around 30-40 square meters of floor.
Option 1 Dynamic Flow Control
'" Uponor Vario S Dynamic Flow Control systems that offer precise circuit adjustment between 30-300 kg/h.
Option 2 Smatrix Move
As an alternative, we can implement Uponor mixing pump groups paired with Smatrix Move climate controllers. These systems are compatible with heat pumps and provide excellent control over your heating system
Option 3 Wilo Stratos MAXO-Z
T-const. control mode: The pump constantly monitors the hot water temperature and adjusts its speed to maintain the desired setpoint. This ensures a consistent and comfortable hot water supply, regardless of usage.
Constant differential temperature (dT-const.)
volume flow optimisation"
Instead of replacing old pipes in concrete, we could consider other options.
I understand - It’s not efficiency as in COP you’re trying to optimize but rather need to get your house to a comfortable temperature level.
I can’t comment on the pumps and their modes as I just have the internal pump of my heatpump. But let’s try some back-of-the-envelope calculations.
I am inferring you need 5 kW of heat power into the circuit in question, but can only get 2 kW due to flow rate restictions. At \Delta T = 5K, 2 kW translates to a maximum flow rate of 5.7 liter/min.
In order to get 5 kW through 5.7 l/min, you’ll need a \Delta T of 12.5 K. Assuming your flowrate is constant at 5.7 l/min, this \Delta T will automatically be reached as you increase your flow temperature to the point where your UFH can shed the 5 kW heat power. As your house is not warm enough at the current conditions, it’s hard to estimate at which temperature this will be reached - I guess that’s a matter of testing.