Install #Bypass #Valve into sealed #heating system with unvented cylinder

How to install bypass valve Honeywell into sealed heating system with unvented cylinder
This is Honeywell bypass that opens the water flow when the pump is working and all circuits are closed
Arrow shows the direction of water flow. White plastic and spring opens the hole under the water pressure
Bypass wasn’t installed by plumber who swapped cylinder and moved it into the loft
We have a sealed system with Y plan and bypass maintains sufficient water flow through the boiler to ensure that the overheat thermostat does not operate under normal conditions
Here we show the main nodes of our system which will be involved in by-pass installation. We have 3 port valve Drayton and 2 port valve Honeywell
What we actually have. We need to cut two pipes and install bypass between pump and 3 port valve
Now we demonstrated the water hammer effect that appeared when CH switches to Water heating
Bypass let to avoid this harmful effect in heating system
To assemble bypass node we use compression fittings
because their installation is cheaper, quicker and safer - no need solder, flux, gas-burner and fire extinguisher
you need compression rings – one for each disassembled joint
If you use old ring you need to apply joint compound to avoid leakage.
Using piece of pipe we adjust it to the necessary length that will be enough to install between pumps and valve
When you have a assembled bypass you can easy define where to cut the pipe and how far the valve will be moved
We need to lift up the pipe with 3 port valve and locate the bypass between pump and valve
The next – drain down the water system
It is under pressure, check that filling point is closed. But there is some pressure into the system.
Turn off the boiler, shut down the power and check the indicator is off.
This is a scheme of our heating system
Bypass will be installed on the upper floor thus we could drain down the system till the installation point
No need to drain down entire system
As the water contains heating liquid we avoided to pour down all water
Lowest point of the system on the ground flow
Attach a length of hose to this drain valve of the toilet radiator and secure it
Run the other end of the hose to a suitable drain off point outside into toilet bowl
The hose should obviously run downhill to allow the water to flow
Open the drain valve by turning the square head with a spanner or small wrench
Pouring some water out of radiator
Check the pressure in system has decreased
To drain dawn the both HW pipes and HS we open 2 port valve(presents on unvented cylinders)
and switch 3 port valve into middle mode when HW and HS are open
Depressurized the upstairs radiator as it still has some pressure
And open the 3 port valve. If there is till some water at this level close valve and repeat the step of pouring water in toilet downstairs and check again till there will be no water
Using the wrench remove the 3 port valve and Drayton actuator, unscrew the old couplers
Actuator might me removed. It has a lock
Then you could cut the pipe in that place where bypass will be installed
Rise the three port valve with additional pipe and install assembled bypass
You need two different wrenches to tighten the compression couplers
when everything has done you may open the water – turn on the tap gently and ensure there is no leakage and pressure is going up
In case of leakage tighten compression couplers.
Using tissue or paper you may check the leakage between the pipe and couplers
Bypass Honeywell is supplied with installation instruction
It is brief instruction into system with combi boiler and system with cylinder
This graphs illustrate how to calculate the pressure for bypass valve
To define the setting you need to know the minimal water flow in the heating system and pump speed
These figures are used to define the pump head using pump’s instruction
When you know the pump head and pump speed you able to define the bypass setting on the second graph
In our system pump speed is 3
Minimal flow according boiler instruction is 540 liters per hour
Then we found the instruction for our pump and define the pump head on the graph which is about 5 meter, that was converted in mill bar. It is about 490 millibar
Then using the second graph in bypass instruction we define the setting is about 3-3,5
This pressure was set up on bypass

Install #Bypass #Valve into sealed #heating system with unvented cylinder

Latest Posts