13-03-2022, 07:50 PM
The prospect of things like Legionnaires disease did cross my mind initially, but then I wondered if Nick has an unvented mains pressure system?
Effectively, these work in reverse. Instead of water from the heat source (boiler or heat pump) going through a coil to heat a mass of stored water to be delivered to the taps, cold water from the mains goes through the coil and is heated by the mass of hot water. This means that practically none of the water appearing at the taps has been stored for any length of time. While the stored water will have additives to inhibit bacterial growth (and corrosion, etc.).
Of course, the heat stored in the mass of water can be "topped up" by other heat sources, such as solar or electricity. The latter is sometimes necessary to reach the desired temperature if the flow from a heat pump isn't hot enough. And of course, as with a conventional gravity-fed system, you have electricity as a backup, should the primary source fail.
BTW, these are not a DIY install, and I'm not pretending to know a huge amount about them, but I do know a few friends who have gone down this route, and it makes a lot of sense in many situations. I've still got a gravity-fed setup, so need to have a pump to supplement the shower. In my case, as I'm coming directly into contact with the stored hot water, I do make sure it's hot enough. The recommended range for stored water is above 50 degrees. And below 20 degrees. So in the warmer months, the cold water storage tank in the loft could also be a risk. With 4 of us here, and the use of a pumped shower, the water is replenished several times a day.
I'm "warmer" to the idea of heat pumps than some. Since moving over to a weather compensated boiler many years ago, the flow temperature to the heating circuit is only above 50 degrees when it's below zero outside. And that's with the same radiators that I had originally. If I upgraded them (and perhaps also included some under-floor heating in the kitchen), I could envisage a heat pump working very well. I'd only go with ground source, but that's not financially viable for me (and as it's a terraced house with a small-ish garden, I suspect it would involve bore-holes). I don't like the idea of noise from air-source units (we have them at work), plus they are obviously much more weather-dependant. There are some vocal critics of heat pumps, and I can see where they're coming from - but a lot of the criticism I've seen is specific to air-source (coupled with a lack of knowledge/experience that makes them blind to the idea that radiators can work at less 70 degrees).
Effectively, these work in reverse. Instead of water from the heat source (boiler or heat pump) going through a coil to heat a mass of stored water to be delivered to the taps, cold water from the mains goes through the coil and is heated by the mass of hot water. This means that practically none of the water appearing at the taps has been stored for any length of time. While the stored water will have additives to inhibit bacterial growth (and corrosion, etc.).
Of course, the heat stored in the mass of water can be "topped up" by other heat sources, such as solar or electricity. The latter is sometimes necessary to reach the desired temperature if the flow from a heat pump isn't hot enough. And of course, as with a conventional gravity-fed system, you have electricity as a backup, should the primary source fail.
BTW, these are not a DIY install, and I'm not pretending to know a huge amount about them, but I do know a few friends who have gone down this route, and it makes a lot of sense in many situations. I've still got a gravity-fed setup, so need to have a pump to supplement the shower. In my case, as I'm coming directly into contact with the stored hot water, I do make sure it's hot enough. The recommended range for stored water is above 50 degrees. And below 20 degrees. So in the warmer months, the cold water storage tank in the loft could also be a risk. With 4 of us here, and the use of a pumped shower, the water is replenished several times a day.
I'm "warmer" to the idea of heat pumps than some. Since moving over to a weather compensated boiler many years ago, the flow temperature to the heating circuit is only above 50 degrees when it's below zero outside. And that's with the same radiators that I had originally. If I upgraded them (and perhaps also included some under-floor heating in the kitchen), I could envisage a heat pump working very well. I'd only go with ground source, but that's not financially viable for me (and as it's a terraced house with a small-ish garden, I suspect it would involve bore-holes). I don't like the idea of noise from air-source units (we have them at work), plus they are obviously much more weather-dependant. There are some vocal critics of heat pumps, and I can see where they're coming from - but a lot of the criticism I've seen is specific to air-source (coupled with a lack of knowledge/experience that makes them blind to the idea that radiators can work at less 70 degrees).
