Consultation with an engineer experienced in designing water supply systems is required.
The system consists of a indirect heating boiler, a boiler, a thermostatic mixing valve, and a circulation pump.
The craftsmen plan to implement a scheme where the recirculation loop goes directly to the boiler, meaning it will not intersect with the thermostatic valve (Scheme 1).
However, there is an opinion that in such a scheme, the recirculation will not work because the valve will be closed. And for it to work, the recirculation loop needs to intersect with the thermostatic valve (Scheme 2).
But the craftsmen warn that in such a scheme, the pump will constantly push towards the valve, which may cause a problem – cold water will enter the loop, causing discomfort when using hot water (shower, faucet).
Meanwhile, the manufacturer ESBE recommends Scheme 3, which, as I understand, is the same as Scheme 2 but with additional check valves.
Also, the craftsmen installed an automatic air vent only on the boiler heat exchanger loop. They caution against installing it on the recirculation loop because constant high pressure of 3-4 bar is not good for the membrane, risking its failure. They claim that water under pressure will constantly push air outwards, so it will not stay in the loop.
However, there is an opinion that installing an air vent is advisable since, in our case, the recirculation pump is located at the highest point of the system (above the boiler under the ceiling), and the presence of air negatively affects its operation. Also, the air vent is rated to operate at a maximum of 10 bar.
In connection with this, the following questions arise:
- Will recirculation work in Scheme 1?
- Is it true that Scheme 2 is more appropriate than Scheme 1?
- Can there really be a problem in Scheme 2 as described by the craftsmen?
- Can Scheme 3 be used?
- Is an automatic air vent needed on the recirculation loop?
- Can there really be a problem with it as described by the craftsmen?
