These Hotpot tanks can be used as either accumulators or expansion tanks. They will assist in the smooth flow of water and are designed to compensate for unequal flows and expansion as the water in the Hotpot calorifier tank is heated to avoid unnecessary pump operation. Their use is especially recommended for multi outlet applications and if the vessel has a shower installed.
Accumulators (used on the cold water side) are set at approximately 12-13psi as they need to be just below the cut in pressure of the pump, so you get the maximum movement from the diaphragm inside the tank. This helps prevent rapid pump on/off cycling and helps to prolong the life and performance of the pump.
Expansion tanks (used on the hot water side) need to be set above the maximum pressure of the pump but below the pressure of the pressure relief valve (PRV). For example, if the maximum pressure of the pump was 30psi and the PRV was set at 40psi you would set the expansion tank at around 35psi. This will mean only water which is being expanded by heat will get into the expansion tank, rather than that from the pressure of the pump.
All Hotpot accumulator / expansion tanks come complete with mounting brackets and a 13mm hose spigot. Most are rechargeable and the larger tanks have replaceable rubber membranes. The tanks are suitable for potable (drinking) water. Only the stainless flange and the butyl diaphragm contact the water.
When choosing an accumulator to use as an expansion tank on the hot water side of the calorifier, choose one which is about 8% of the calorifier capacity.