Understanding Boiler and Megalfow

yaz2010

Hi members,
I have moved into a new home which has Worcester Greenstar 30 CDI conventional boiler downstairs and a Megaflow Heatrae Sadia on the first floor.
There is a honeywell ST6400C thermostat for the controls next to the boiler.

I want to know do I have to keep the hot water on a CONTINUOUS mode or do I set it for few hours Morning/Evening like we do for central heating. I want to make sure I am not wasting money on gas/electricity bill.

Previously had a combi boiler in a flat so never really had to do much.

It takes a minute roughly for the hot water to start flowing whenever we open the tap.

What are your views?

Thank you.

huckster

I think it would depend on how many people are in the house and when you are using the services. If you don't have much demand and are out most of the day, then I would just have the heating on morning and evening, with just water heated at the same time. I think the megaflow is a separate water heater/hot water storage cylinder and some of these can be expensive to run, so you would not want it on all the time. The megaflow as I understand it, is a modern replacement for the old copper hotwater storage tank, which has an immersion heater.

yaz2010

Its just 2 people in the house.

huckster

So just have Worcester boiler timed to come on in the morning and evening. Don't use the Megaflow to heat water.

If you are around more often for periods, you can switch the Worcester boiler on for longer.

It is probably not going to be a system that is as cheap to run as your previous homes combi boiler.

yaz2010

How do I stop Megaflow from heating the water?

huckster

yaz2010 wrote: »

How do I stop Megaflow from heating the water?

I think you need to speak to a central heating company about your system. The Megaflow cylinder is apparently a pressurised system that may need to be switched on all the time, as it is not just maintaning hot water, but it is also providing adequate water pressure for all of your needs e.g showers.

I thought they were just a storage cylinder, but they are a more than that by the sounds of it. If you switch it off, you might not have very good pressure to showers and the water might not be as hot as you would want.

jennifernil

Surely what the OP has is a pressurised system where the HW is heated by the CH boiler?

This means that the HW is at mains pressure, so good for showers. The heating of the water is no different from a system where the HW cylinder is supplied via a cold water storage tank.

My daughter has this system, she just leaves the HW on all the time when not going away on holiday. These new cylinders are very well insulated.

yaz2010

Hi jennifernil , Do you know if by leaving the HW on all the time, does that cost a fortune?

huckster

jennifernil wrote: »

Surely what the OP has is a pressurised system where the HW is heated by the CH boiler?

This means that the HW is at mains pressure, so good for showers. The heating of the water is no different from a system where the HW cylinder is supplied via a cold water storage tank.

My daughter has this system, she just leaves the HW on all the time when not going away on holiday. These new cylinders are very well insulated.

You may be correct. The OP was asking about the best way to stop wasting money and I was not sure whether the Megaflow was heating water when it did not need to be. If it is, then I would expect that the electricity bill will be higher than expected. As you say they are apparently well insulated cylinders, so this may not be an issue.

jennifernil

But if he has Gas CH then the boiler will also heat the water. No electricity involved other than for the pump and boiler controls.

The cylinder will also have an electric immersion heater but that is just for back-up and would normally be turned off.

jennifernil

yaz2010 wrote: »

Hi jennifernil , Do you know if by leaving the HW on all the time, does that cost a fortune?

I think she pays about £40 a month for gas, that's for a 4 bed 3 storey house with 3 bathrooms. However, there are only 2 adults to use HW .

It's a new house so extremely well insulated.

We have an older system (not pressurised) and also leave the HW on all the time as we are home all day. Our gas bills are higher, but our house is about twice the size.

I expect leaving it on is slightly more expensive, but we prefer the convenience of having HW there when we need it.

Why not try a week leaving it on, and a week timing it, when conditions are otherwise the same (same CH times, same number of showers etc) and see how the gas usage compares?