Hot water & Heating at same time

EScifo

HI,

I recently got a Vitodens100-W boiler installed and when the water is being heated the heating switches off. This is for the duration of time it takes to heat up the water. Is this expected behaviour? Doesn't seem right to me. I asked the plumber about this and he said it was because I had the water setting too high (I had it at 5 I think). I have since turned it down to 3 but it still happens. It is only a minor irritant but still.

thanks

antoinolachtnai

I am having this boiler fitted at the moment. The engineer at the merchant took some time to explain this to the installer and got him to make sure to explain it to me.

Basically, the reason is that this is how the diverter valve in the boiler is made. It is set up so that only one of the two circuits can be active at once.

This sounds weird, but there seems to be a good reason for it. The reason is that the boiler is designed to allow you to send much hotter water to the HW circuit than the CH circuit. It does this to maximize efficiency when heating the CH, but to maximize speed and ensure a high water temperature when heating the HW.

The boiler cannot have two different temperatures feeding to the two circuits at the same time. So that is why they use this type of diverter valve to feed one circuit only at a time.

It looks like it is possible to use a two-channel timer to run the two separately, i.e, you heat the hot water separately, then you switch over to heating-only. I am not certain that this can be done.

This might sort of address your problem because it will mean that the heating will run exactly when you expect it to.

anuprising

your installer has it on the four pipe set up -dhw circuit takes priority over the heating circuit ,like a combi

if you want to heat the two circuits at the same time or one or the other you can choose to set it up on two pipes and zone it like any other boiler ,you will lose some of the plug and play options for controllers etc

third option would be to install a duel coil cylinder ,run your heating circuit thru one coil (which can be off at cylinder if you wish ) and the other coil to your dhw circuit ,best of both worlds and all the features of the boiler are still open to you ,so if you have heating set to come on in morning it will heat water on that circuit(second coil) also . during the day if you just want hot water its on the dhw circuit (first coil) no heating on -

antoinolachtnai

Can you run the CH without the HW?

EScifo

EScifo wrote: »

HI,

I recently got a Vitodens100-W boiler installed and when the water is being heated the heating switches off. This is for the duration of time it takes to heat up the water. Is this expected behaviour? Doesn't seem right to me. I asked the plumber about this and he said it was because I had the water setting too high (I had it at 5 I think). I have since turned it down to 3 but it still happens. It is only a minor irritant but still.

thanks

What you lose in heating performance you gain in hot water reheat performance as you cylinder will achieve temperature quicker than if it had a standard boiler set up, also as mentioned you can have a lower temperature on your heating circuit which can help with fuel economy, I'd love to have your boiler:)

antoinolachtnai

Other suggestion is - setting on thermostat on your hot water cylinder -.

You could turn this down a bit, and then turn the hot water temperature on your boiler up to maximum. This will mean that the hot water cylinder will reach its temperature more quickly.