This is my first post in this forum, but I have been lurking here for a couple of years as have previously found it to be a mine of useful information.
My current system comprises a Vaillant ecoTec 637 (37kw) boiler with Vaillant eBus controls (VRC 470, VR61 2 zone centre, VR81) and a vented 225L cylinder.
I intend to replace the vented cylinder with an unvented one to allow me to lose the cold water storage tank in the loft as I am planning a loft conversion that will add another 2 bedrooms and 2 ensuites (bringing total for house to 6 bed/4 bath).
I had originally intended to go with a Vaillant Unistor 310L unvented cylinder as I have been very happy with the quality & reliability of my current Vaillant system. However one of the plumbing companies I have asked to quote (who installed my current system a couple of years ago) suggested using a dual coil cylinder and feeding both coils simultaneously from the ecoTec 637.
The cylinder suggested was a Grant DuoWave Indirect 300. This is marketed as a solar cylinder with the (smaller) top coil fed from a primary heat source like a gas boiler and the bottom (larger) coil from a solar system).
The plumbing company advised that the Grant cylinder, because of it's dual coils, has twice the surface area of the single coil in the Unistor 310L which should significantly reduce the cylinder recharge time (& reduce the amount of time that heat is diverted away from the space heating with the system configured in DHW priority mode).
This all seems sensible to me, however, a 2nd company that I asked for a comparative quote advised that this wasnt a configuration supported by the cylinder manufacturer.
This does make me wonder, if feeding a dual coil cylinder from a single heat source could provide the above benefits, why manufacturers dont support this?
I have searched this & other forums and cant find another example of anyone else using a dual coil cylinder in this way, hence the reason why I thought I would throw the question open to the experts in this forum
Thanks a lot for your help.
My current system comprises a Vaillant ecoTec 637 (37kw) boiler with Vaillant eBus controls (VRC 470, VR61 2 zone centre, VR81) and a vented 225L cylinder.
I intend to replace the vented cylinder with an unvented one to allow me to lose the cold water storage tank in the loft as I am planning a loft conversion that will add another 2 bedrooms and 2 ensuites (bringing total for house to 6 bed/4 bath).
I had originally intended to go with a Vaillant Unistor 310L unvented cylinder as I have been very happy with the quality & reliability of my current Vaillant system. However one of the plumbing companies I have asked to quote (who installed my current system a couple of years ago) suggested using a dual coil cylinder and feeding both coils simultaneously from the ecoTec 637.
The cylinder suggested was a Grant DuoWave Indirect 300. This is marketed as a solar cylinder with the (smaller) top coil fed from a primary heat source like a gas boiler and the bottom (larger) coil from a solar system).
The plumbing company advised that the Grant cylinder, because of it's dual coils, has twice the surface area of the single coil in the Unistor 310L which should significantly reduce the cylinder recharge time (& reduce the amount of time that heat is diverted away from the space heating with the system configured in DHW priority mode).
This all seems sensible to me, however, a 2nd company that I asked for a comparative quote advised that this wasnt a configuration supported by the cylinder manufacturer.
This does make me wonder, if feeding a dual coil cylinder from a single heat source could provide the above benefits, why manufacturers dont support this?
I have searched this & other forums and cant find another example of anyone else using a dual coil cylinder in this way, hence the reason why I thought I would throw the question open to the experts in this forum
Thanks a lot for your help.