Y plan and questions

cerastes

Few questions in relation to Y plan.
I had come across a great web link but can't locate it now, it described the operation of valves, in particular the mid position diverter valve.
It did say that it was better to leave the valve in one position lastly to prolong its life as one end position isn't powered and the other is still stalling, anyone any links or ideas on this? i.e. I believe it was if shutting off the CH, that its better to demand HW And then shut off the CH, I can't recall it but it was suggesting always demand both before shutting the other off and shut one in particular off first? I'd already spent a bit of time trying to get my head around the operation of the mid position valve.
I thought that the valve just became unpowered but the site seemed to suggest doing it the opposite way left it permanently stalling and prematurely burning out the motor.

The other thing is, I noticed that where both HW and CH being called for, if the HW shuts off and the CH is still being called for that the boiler shuts off for a few seconds, even though the programmer and the stat are still calling for the CH zone, I thought this was a room stat problem but think that the HW off demand and the valve repositioning itself may be shutting off power until it finds its position, anyone come across this?

cerastes

Any opinions on the above in relation to not prematurely burning out the diverter motor over time? in the second paragraph? Is this a known feature/characteristic of Y plan? Or do I have some other problem?

Edit originally I thought it was a problem with the room stat but I think it may be when the valve changes position to account for the HW turning off that it opens a switch inside the valve which shuts off the CH momentarily before it repositions itself and realises its meant to be on.
So maybe the valve is at fault or it just happens on a Y plan?

cerastes

there is no urgency on replying, take your time
its just something Ive been thinking about, all the same if anyone knows??

antoinolachtnai

There is indeed one wrong position. If you consult the manual on any of these devices or call the technical helpline you will find out the definitely-correct answer.

You need an appropriate controller to operate this valve. The wiring is very unintuitive indeed. If you have the right controller, the controller will be set up not to leave the valve in the wrong position.

If you are building some sort of custom controller, I would suggest that when the heat is not running that the valve be unpowered.

There is no power sent to the motor when hot water only is called, with the valve in mid position or heating only power will then be sent to the motor to keep the valve in these positions(making the valve very very hot which can have a negative impact on the valve)

You can improve motor longevity by having your hot water firing separately to your heating, keeping the valve well ventilated will also have a positive impact.

Thankfully the motors on these valves are usually design to be swapped out easily.

There is movement of the switching mechanism from mid-position to heating only so it wouldn't surprise me if that impacts on the boiler(if it's a gas boiler it should have a permanent live making any switching less noticeable)

cerastes

gary71 wrote: »

There is no power sent to the motor when hot water only is called, with the valve in mid position or heating only power will then be sent to the motor to keep the valve in these positions(making the valve very very hot which can have a negative impact on the valve)

You can improve motor longevity by having your hot water firing separately to your heating, keeping the valve well ventilated will also have a positive impact.

Thankfully the motors on these valves are usually design to be swapped out easily.

There is movement of the switching mechanism from mid-position to heating only so it wouldn't surprise me if that impacts on the boiler(if it's a gas boiler it should have a permanent live making any switching less noticeable)

OK. Thanks to all for the replies, clarifies things.
There is no permanent live on the boiler according to the manual so I'd doubt there is any within the wiring, i suspected it was the case with the switching off temporarily when HW was turned off, i was thinking it might be worth looking into having some relay switch a live for when the heating zone is calling, but I'd say it probably doesn't present a significant issue in terms of cycling uneccesary.
It may be possible to overcome it by altering the time settings that call for heat/hot water anyway, which is something I'm going to look at to counter the possibility of the valve being left in the wrong (probably better to say least preferred) position lastly.
At some point the heating will be demanded either on its own or jointly with the hotwater, I'm not sure if setting the demand separately would help as you say the valve is in a potentially hot/stalled position when supplying hotwater to the rads when heat is demanded ? But it seems that leaving the valve in the hot water position lastly at any period of heat demand would eliminate this?

I think I have my head around it a bit better, its mostly to be informed and out of interest as the boiler is older anyway, but fingers crossed otherwise functional, I've researched what boiler to get in the event of it clapping or being uneconomical to repair. I'd prefer this one held out for a while but I might consider altering to an S plan if the boiler is upgraded, that's if installing such 2 port valves don't operate in a stalled manner tto maintain open position, although thinking about it, they probably do unless they have 2 internal switches to control them.

Thanks for the replies.

cerastes

cerastes wrote: »

OK. Thanks to all for the replies, clarifies things.
There is no permanent live on the boiler according to the manual so I'd doubt there is any within the wiring, i suspected it was the case with the switching off temporarily when HW was turned off, i was thinking it might be worth looking into having some relay switch a live for when the heating zone is calling, but I'd say it probably doesn't present a significant issue in terms of cycling uneccesary.
It may be possible to overcome it by altering the time settings that call for heat/hot water anyway, which is something I'm going to look at to counter the possibility of the valve being left in the wrong (probably better to say least preferred) position lastly.
At some point the heating will be demanded either on its own or jointly with the hotwater, I'm not sure if setting the demand separately would help as you say the valve is in a potentially hot/stalled position when supplying hotwater to the rads when heat is demanded ? But it seems that leaving the valve in the hot water position lastly at any period of heat demand would eliminate this?

I think I have my head around it a bit better, its mostly to be informed and out of interest as the boiler is older anyway, but fingers crossed otherwise functional, I've researched what boiler to get in the event of it clapping or being uneconomical to repair. I'd prefer this one held out for a while but I might consider altering to an S plan if the boiler is upgraded, that's if installing such 2 port valves don't operate in a stalled manner tto maintain open position, although thinking about it, they probably do unless they have 2 internal switches to control them.

Thanks for the replies.

As you have a 3 port fitted already I'd look at fitting a W-plan which gives you priority hot water allowing you to remove the hot water KW requirement when sizing a boiler.

antoinolachtnai

I have this W-plan sort of arrangement (with the valve inside the boiler, a Viessmann).

I really like it. However, lots of people find it unintuitive that the hot water and heating can't be on together. The hot water has to heat up before the heating will start, if you put them both on at the same time.

This is more likely to be a problem if you have a tank which takes a while to heat. If you get a modern, fast recovery tank, this won't be much of an issue.

cerastes

gary71 wrote: »

As you have a 3 port fitted already I'd look at fitting a W-plan which gives you priority hot water allowing you to remove the hot water KW requirement when sizing a boiler.

A W plan, hadn't even looked into it, we seem to use very little hot water, the tank being on or hot water being required always seemed to be less of a priority to space heating when heating is required, in this weather we rarely turn on the boiler, although I operate it so its not been off for ages and make use of the hot water , I need to look into W plan more really. Removing the HW requirement would seem to be an advantage in sizing and an I interesting suggestion given I haven't heard it recommended before, bht I'm not sure if this means the heating only comes on when the HW demand is satisfied? I suppose the stat for the HW could be set low? And alternate a high value once a week.
To that end I'm considering getting a programmable stat for the tank, I can see only be make, all with the view to controlling the HW setting at a lower level but automatically going high at least once a week.

At the moment I'm happy enough with Y plan for my current set up. I won't rule anything out in the futur e but at that stage my vlve may have suffered too much wear and tear,

3port vales are the most common type of valve fitted across the water and W plan would used the most to allow for smaller boilers to be fitted.

If home owners took time to understand their own heating controls and If the controls are fitted correctly the home owner would soon adapt the heating and hot water to suit their own needs, I don't recall to many complaints/problems about W plans or Y plans from those who had them as they could usually be able to interact with their heating system to get what they want.

antoinolachtnai

cerastes wrote: »

A W plan, hadn't even looked into it, we seem to use very little hot water, the tank being on or hot water being required always seemed to be less of a priority to space heating when heating is required, in this weather we rarely turn on the boiler, although I operate it so its not been off for ages and make use of the hot water , I need to look into W plan more really. Removing the HW requirement would seem to be an advantage in sizing and an I interesting suggestion given I haven't heard it recommended before, bht I'm not sure if this means the heating only comes on when the HW demand is satisfied? I suppose the stat for the HW could be set low? And alternate a high value once a week.

No. There are three settings

HW
CH
HW+CH

If you put it on HW or CH it is pretty obvious what will happen.

If you put it on HW+CH then the HW will run until the thermostat is satisfied, then the CH will run.

For your situation, you'd just run the CH. Once a week, you would run the HW.

However, you would have no HW whatsoever except on the day you run the HW. So you would probably need to run it a few times a week.

The one thing with all this stuff is not to make everything too complicated. It is just a house after all.

cerastes

cerastes wrote: »

A W plan, hadn't even looked into it, we seem to use very little hot water, the tank being on or hot water being required always seemed to be less of a priority to space heating when heating is required, in this weather we rarely turn on the boiler, although I operate it so its not been off for ages and make use of the hot water , I need to look into W plan more really. Removing the HW requirement would seem to be an advantage in sizing and an I interesting suggestion given I haven't heard it recommended before, bht I'm not sure if this means the heating only comes on when the HW demand is satisfied? I suppose the stat for the HW could be set low? And alternate a high value once a week.
To that end I'm considering getting a programmable stat for the tank, I can see only be make, all with the view to controlling the HW setting at a lower level but automatically going high at least once a week.

At the moment I'm happy enough with Y plan for my current set up. I won't rule anything out in the futur e but at that stage my vlve may have suffered too much wear and tear,

Your over thinking your controls so as above let's not over complicate things:).

You have a Y plan so if it was me I would via a two channel programmer separate the times the boiler fires for heating and hot water so the two are never really on at the same time.

The benefit to this is it easier to balance the heating circuit during installation, the reheat times for your cylinder is greatly improved so waiting for the hot water to heat in the first place is less of a issue and you improve the longevity of the motor in your valve.


If you were to replace the Y plan for a W-plan you still get the benefits as above but you can reduce the boiler size as the heating and hot water physically can't be on at the same time.


The main point you need to understand with a Y-plan is when both hot water and heating are calling for heat then sharing that heat produced by the boiler you then have a hot water cylinder that will take longer to heat and you also have a heating system that can be unbalanced taking longer to achieve temperature.