Hot Water Cylinder Set-up

[jon26]

Just after some advice please, hot water installation on a very large house. The owner would like to have 2 cylinders; one to serve the two bathrooms that the owners will tend to use more often, and the 2nd to serve three bathrooms that would only be used when guests are staying over.

1.Would the best method of doing this be a separate flow and return circuit from the boiler to each cylinder with separate timer control so they can turn on the additional cylinder when needed?

2.My only concern was that because this is a very large house (600m2!) and the bathrooms are spread all over the place, there would therefore need to be a HW secondary loop on each cylinder, but I don't think there is any way around that?

3.Would it be a good idea to link the hot water from both cylinders so that additional hot water could be obtained if they need it?

The house is huge (5 bathrooms total, lots of belfast sinks etc.) so each cylinder would be at least 300 litre capacity.

Thanks

 

[ajstoneservices]

If you link them directly or via the secondry return you're gonna end up heating 600l when only 300l is needed.

Are they going to be copper or stainless cylinders, I wouldn't want to store water in a stainless cylinder that is likely to sit between 20-50c for any length of time you will need to heat the cylinder to 60c for at least 1 hour a week.

 

[jon26]

My thoughts were to feed each cylinder with separate flow and returns (controlled by a zone valve on each circ) to control each cylinder separately. Like you say I don't want to be heating 600 litres of water when only one of the cylinders is mainly needed.

I would be using 2 unvented cylinder, Megaflo's or something like.

Its just the HW loop which I can't get my head around, there would have to be 2 loops one from each cylinder presumably = lots of pipework running around the house.

Is there any other way of doing it?

 

[Dan Robinson]

You'll need two totally separate DHW systems.

As AJ said - legionella will play a part too.

 

[ajstoneservices]

You'll need two totally separate DHW systems.

As AJ said - legionella will play a part too.

 

[ajstoneservices]

My thoughts were to feed each cylinder with separate flow and returns (controlled by a zone valve on each circ) to control each cylinder separately. Like you say I don't want to be heating 600 litres of water when only one of the cylinders is mainly needed.

I would be using 2 unvented cylinder, Megaflo's or something like.

Its just the HW loop which I can't get my head around, there would have to be 2 loops one from each cylinder presumably = lots of pipework running around the house.

Is there any other way of doing it?

It will be far simpler to treat them as two systems. A couple of returns shouldn't be that difficult, run em in Hep.

 

[jon26]

My thoughts were to feed each cylinder with separate flow and returns (controlled by a zone valve on each circ) to control each cylinder separately. Like you say I don't want to be heating 600 litres of water when only one of the cylinders is mainly needed.

I would be using 2 unvented cylinder, Megaflo's or something like.

Its just the HW loop which I can't get my head around, there would have to be 2 loops one from each cylinder presumably = lots of pipework running around the house.

Is there any other way of doing it?

It will be far simpler to treat them as two systems. A couple of returns shouldn't be that difficult, run em in Hep.

Yes, I think the most effective way would be to treat them as two systems, with two hot water loops, is that what you are suggesting?

What would happen to circulation pump serving the hot water loop on the cylinder which will be used less frequently, would this just run all the time? Otherwise you would need to turn the pump on when the additional cylinder was needed. I can't quite get my head around the best way to do it.

 

[bgs100engineer]

fit an S plan but add an extra zone valve, with is own controls. that is time switch and cylinder stat. when you branch of from the pump, fit auto by-pass first then have the pipe work split into three with a 2 port valves on each branch, have this close to the 10 way J/B as you`ll use less wire. So you`ll have one zone valve for the heating and one for each cylinder circ`s. you could fit the system with one pump for the heating and one for the both cylinder circ`s but you would requires two auto by-pass valves, this would reduce wear on the pumps. still using the three zone plan though. The time could switch the other cylinder on once a week for and hour. problem solved. check your honeywell wiring plans, easy.

hope this helps

 

[jon26]

fit an S plan but add an extra zone valve, with is own controls. that is time switch and cylinder stat. when you branch of from the pump, fit auto by-pass first then have the pipe work split into three with a 2 port valves on each branch, have this close to the 10 way J/B as you`ll use less wire. So you`ll have one zone valve for the heating and one for each cylinder circ`s. you could fit the system with one pump for the heating and one for the both cylinder circ`s but you would requires two auto by-pass valves, this would reduce wear on the pumps. still using the three zone plan though. The time could switch the other cylinder on once a week for and hour. problem solved. check your honeywell wiring plans, easy.

hope this helps

That helps, thanks very much. I was thinking of the same set-up. Is there any set rules on when to switch the other cylinder on, you mentioned once a week for an hour, I assume that is all thats needed?

Just one other thing; its the bronze pump on this cylinder - there will be times when the cylinder is not in use, would you still have the bronze pump circulating, otherwise you would need to turn the bronze pump on every time the 2nd cylinder was needed?

Thanks

 

[Dan Robinson]

Wire the bronze pump into the seconds cylinder controls. Maybe using the switched live from the main controller of the second cylinder's heat source controller to the common of the bronze pump timer.

 

[jon26]

Wire the bronze pump into the seconds cylinder controls. Maybe using the switched live from the main controller of the second cylinder's heat source controller to the common of the bronze pump timer.

Great idea. Thanks

 

[Bambergaspipe]

Great idea. Thanks

Not really your best option is to go with an unvented cylinder, this will give you hot water at mains pressure,

 

[jon26]

Great idea. Thanks

Not really your best option is to go with an unvented cylinder, this will give you hot water at mains pressure,

Don't quite understand what you are saying. I always was going with an unvented cylinder. The questions were relating to set-up and controls.

 

[Bambergaspipe]

Don't quite understand what you are saying. I always was going with an unvented
cylinder. The questions were relating to set-up and controls.

Pardon my ignorance, no one mentioned unvented, I forgot my crystal ball, silly me.. just re -read someone mentioned bronze pump and secondary return. or was that me? Did I mention secondary return..

 

[jon26]

Don't quite understand what you are saying. I always was going with an unvented
cylinder. The questions were relating to set-up and controls.

Pardon my ignorance, no one mentioned unvented, I forgot my crystal ball, silly me..

I see what you mean, I thought I'd mentioned unvented in the posts.. sorry. I think 'unvented' is a given nowadays though