Wanted to get some of you clever peoples opinions. Is a geyser blanket worth its cost and if so what is the rough payback period on say a 150l Kwikot geyser, I have changed the element to a 2Kw. I have 2 150l geysers in the house, the one feeds the kitchen +_ 15m from the geyser, this also feeds my sons bathroom, this still has a 3kw element. The other 150l geyser feeds the main bathroom (shower only). All geysers are controlled via an Astute smart switches in the DB board. I do have solar (5kw SunSynk, 14.3Kwh of battery, soon to be 28.6Kwh), wanted to try and save as much power in order to charge my 2 batteries. So if a blanket would help the loses it might be something I would do.

Edited January 22Jan 22 by Greglsh

I would rather spend my money on pipe (hot & cold) lagging

I think @Virwat has it. My geyser is insulated with a layer of isothem (not an actual blanket that you buy from a shop), and the hot pipes are insulated from the geyser to the wall with the same material. The hot pipes radiate heat, so there is a gain to be had by reducing those losses.

Do timers on a geyser save money? This is an old and inconclusive debate. But we can cut our losses from the geyser once it is heated. Or we can heat it more efficiently.

I don't think that timers save you money, but you can control when it heats so mine only heats when the sun comes up so probably costs the same but my solar is heating most of it. Is this the type of "lagging" you guys are using on your pipes?

Edited January 22Jan 22 by Greglsh

Heater blankets for geysers may be efficient if you have one that's mounted on an outside wall. I am not convinced it makes much of a difference inside the roof .
Pipe insulation on the other hand will make a bigger difference as the pipes themselves will heat up quicker whilst eliminating radiative losses to the surrounding cooler air.

My take on geysers is that the thicker the polyurethane in the geyser the better, 60mm, preferred or more, but have not found geysers with more. And then pipe lagging, on all the pipes, cold inlet, hot outlet (for at least 2-4 meters, maybe even better, if it can be almost to the tap and overflow/TP valve and pipe to reduce losses. One problem I have with lagging to the tap is the pipes are not lagged in the walls and hot water pipe loses a large amount of heat to the walls in winter.

Timers make no difference, has been my experience, or so little it's negligible. However if you are going to be away for for few days, turn the geyser off, it will save some power, as the geyser will not have try and maintain the geyser temp.

The amount of energy used to heat the geyser from, is pretty consistent, but obviously variable based on the starting temp and resultant temperature.

So all a timer allows for is remote control or a way to load shift, not really reduce the energy required?

One larger geyser is better than many, but can cause more water wastage? due to initial cold water in the pipes? unless you are draining the water into grey water tanks and using it in the garden? or if you have a diverter valve under the counter with each tap that drains the cold water to an alternative pipe which go's to a JOJO tank which can then be used for other uses, once the water heats up the valve allows the hot water out the tap rather than diverting it. Can't recall what the diverter valve is called but saw them some years back. as a water saving otion. Downside Is one has to have a third pip for the initial cold water diversion, at each tap, and or bathroom etc. so best if you are planning to build or do renovations / upgrades.

Last thought is to charge batteries first, keep load low, until fully charged, especially in winter, and then only start heating the geyser with "excess / available" pv power :)

Edited January 22Jan 22 by Arandoza

1 hour ago, Greglsh said:

Wanted to get some of you clever peoples opinions. Is a geyser blanket worth its cost and if so what is the rough payback period on say a 150l Kwikot geyser, I have changed the element to a 2Kw. I have 2 150l geysers in the house, the one feeds the kitchen +_ 15m from the geyser, this also feeds my sons bathroom, this still has a 3kw element. The other 150l geyser feeds the main bathroom (shower only). All geysers are controlled via an Astute smart switches in the DB board. I do have solar (5kw SunSynk, 14.3Kwh of battery, soon to be 28.6Kwh), wanted to try and save as much power in order to charge my 2 batteries. So if a blanket would help the loses it might be something I would do.

Yes a geyser blanket can be worth the cost on your 150 L geyser(s), but how much you’ll save and how quickly you recoup the cost depends on a few key factors about your usage patterns, insulation quality and your system’s electricity costs.

A geyser blanket adds extra insulation around the hot water cylinder, reducing how much heat your water loses to the surrounding environment. Less heat loss means, less frequent reheating cycles, lower energy consumption to keep water at temperature and less draw from grid or batteries. On a 150 L geyser without good insulation, typical daily standing losses are about 1.5–2.5 kWh/day. With a good blanket installed, those losses might drop by ~30–50% (0.5–1 kWh/day saved).
So, potential daily savings 0.5 kWh to 1 kWh per geyser per day. That’s about 15–30 kWh per month per geyser just from reduced heat loss. Also insulate the pipes hot and cold around the geyser especially the first few meters to cut heat loss.

With your Astute smart switches, you can avoid heating outside your main usage window and set the right thermostat temperature around 55–60 °C is generally enough for showers or baths without wasting energy heating hotter than necessary.

Kwikot Geyser Blanket

Reduces domestic electric water heater and solar water heater heat loss For in ceiling domestic water heater and solar water heater installations

Numbers! 👏