I havebeen trying to discover the precise definition of a “one-pipe system” forcentral heating radiators. I know what atwo-pipe system is.
For aone-pipe system, there “appear” to be two possibilities:
Possibility1: The pipe carrying water from the pump enters the first radiator at the handvalve. The water flows through theradiator and exits at the lock shield valve. The water then flows on to the next radiator in sequence, and so on. In this configuration, there is only a singlepath for the water to flow through all the radiators in the system.
Possibility2: The pipe carrying water from the pump reaches the first radiator. The pipe then divides into two just beforethe hand valve. Some water flows throughthe hand valve into the radiator but some flows along the other pipe therebybypassing the radiator. The water exitingthe radiator at the lockshield valve enters a pipe that joins the bypass pipe,so that there is then a single pipe that carries the water onto the nextradiator in sequence, and so on.
Which ofthese two possibilities is a “one-pipe system”. Or are they both possibilities?
Eachpossibility will have different attributes. For example, you could not have any TRVs in a Possibility 1 system because,when the first TRV closes, it would stop all the water from flowing. But you could have TRVs in a Possibility 2system. And, if the pipes carrying waterbetween the radiators are hidden underneath the floorboards, it might be relativelyeasy to detect whether you have a Possibility 1 system. But it might not be so easy to distinguish betweena Possibility 2 system and a two-pipe system.
For aone-pipe system, there “appear” to be two possibilities:
Possibility1: The pipe carrying water from the pump enters the first radiator at the handvalve. The water flows through theradiator and exits at the lock shield valve. The water then flows on to the next radiator in sequence, and so on. In this configuration, there is only a singlepath for the water to flow through all the radiators in the system.
Possibility2: The pipe carrying water from the pump reaches the first radiator. The pipe then divides into two just beforethe hand valve. Some water flows throughthe hand valve into the radiator but some flows along the other pipe therebybypassing the radiator. The water exitingthe radiator at the lockshield valve enters a pipe that joins the bypass pipe,so that there is then a single pipe that carries the water onto the nextradiator in sequence, and so on.
Which ofthese two possibilities is a “one-pipe system”. Or are they both possibilities?
Eachpossibility will have different attributes. For example, you could not have any TRVs in a Possibility 1 system because,when the first TRV closes, it would stop all the water from flowing. But you could have TRVs in a Possibility 2system. And, if the pipes carrying waterbetween the radiators are hidden underneath the floorboards, it might be relativelyeasy to detect whether you have a Possibility 1 system. But it might not be so easy to distinguish betweena Possibility 2 system and a two-pipe system.
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