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Two Hot Water Cylinders


Onoff

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BEFORE everyone starts shouting UVC/TS.....

 

Is there ever a case whereby TWO hot water cylinders are fitted in a property?

 

Thinking on the cheap and my own situation. A big, long house with the oil boiler at ground floor and the copper hot water cylinder directly above in the loft. Kitchen is immediately adjacent to the boiler at ground.

 

Hot to the kitchen taps is pretty instant having so little distance to travel.

 

Hot to the other end of the house where the d'stairs cloak, new downstairs bathroom and upstairs en suite is takes forever to get there with the taps running cold for ages. What I could do with is ANOTHER cylinder the other end of the house. All I'd need is to insulate the hell out of the boiler feed to the remote cylinder. The existing 25gal cold water storage tank above the dormer roof is too small but couldn't I "double the head" by installing ANOTHER 25 gallon cold water storage tank the other end. In effect I'd be mirroring what I've already got.

 

Traditional, simple and CHEAP!

 

 

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A solution is a pump and return pipework - in effect circulate the water from the DHW to the other end of the house. Yes this will cause you to lose heat, but so will having a 2nd DHW with long boiler pipe runs. You can control the pump with a timer e.g. in the morning and evening when you need to use the bathrooms at the other end.

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Absolutely nothing wrong with having two cylinders we came across this pretty often more so in older installations.

Another option is a hot water loop with a pump which cuts the time running cold water for hot.

Just a idea.... could you not run the DHW pump (obviously not direct)when you switch the bathroom lights on ?

 

 

Edited by Alexphd1
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Lack of capacity is certainly a factor. You would need to think about the sequence of heating and controls for that to work as well - e.g. heat tank 1 first and only then tank 2. So then what happens if you need hot water from tank 2 but tank 1 is being heated.

 

It sounds a bit complex to me. One big cylinder would be my first preference.

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43 minutes ago, ragg987 said:

Lack of capacity is certainly a factor. You would need to think about the sequence of heating and controls for that to work as well - e.g. heat tank 1 first and only then tank 2. So then what happens if you need hot water from tank 2 but tank 1 is being heated.

 

It sounds a bit complex to me. One big cylinder would be my first preference.

 

Hypothetically then with two cylinders & two cylinder stats I'd maybe need two valves so the boiler only feeds whatever tank is depleted heat wise.

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Simple W Plan with a 3 way diverter valve and have a "primary" tank and a "secondary" tank. When the primary is satisfied then the secondary gets heat. 

 

I mustn't be the only one thinking an inline electric heater may be simpler ..?? One of the 12kw Siebel ones would certainly help and it's something that would stay in place once you get round to sorting the UVC...

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59 minutes ago, SteamyTea said:

Are they both used equally as much, or is one for guests or mainly showering?

 

Tbh the hot in the kitchen is used for washing hands and the odd really greasy job that can't go in the dishwasher. The majority "requirement" is at the other end of the house; basins, bath & showers. Third is opposite end to where the cylinder is.

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Are you on mains gas?

Sorry just re read it and your own oil. A oil boiler will have no problem heating both tanks at the same time.Don't think you will have a problem with controls I personally would just add a extra 2 port valve through a tank stat and controlled by a standard timer. You can get multiple channel timers but they tend to be expensive, easier with a extra single channel timer (combi boiler timer) above your existing controls for the extra tank.

Edited by Alexphd1
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Ok so here's a random thought...

 

Take the secondary loop off the current tank and circulate it to a separate direct cylinder at the other end of the house. You're basically doubling the size of the current tank and it would technically mean that the second tank is always at the same temperature as the first and it could be done with two lengths of 22mm and a pump with timer set to say 15min/Hr. 

 

No separate header and the plumbing would be reasonably simple. 

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9 minutes ago, Alexphd1 said:

What's wrong with DHW loop by a pump?

 

I like @PeterW's idea as it gives capacity.

 

I should have added that I've already gotten hold of a 2nd hand copper cylinder that tbh doesn't look that old where the people changed to a combi. 

 

Edit: But it's indirect... :(

Edited by Onoff
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9 minutes ago, PeterW said:

Doesn't matter - just cap the coils off ..!

 Got it. Single coil on this. So.....

 

I come out of the top of the original tank and into the bottom of the new one with a length of well insulated 22mm. Would i need a pump?

 

I could take off DHW then from either?

 

I assume I'd need an expansion pipe from the second tank?

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It seems to me that you are set on a secondary cylinder, so can you lag all pipework well to reduce losses?

It is just like electrical wiring, except backwards, you need to insulate it well, odd I know, kind of goes against the grain, even for most plumbers xD

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45 minutes ago, Nickfromwales said:

This is only NOT mental IF your not doing the UVC anytime soon :/

Even more so if you go for another header tank. 

 

Said the voice of reason shaking his head and wondering why he bothers... :)

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5 hours ago, Onoff said:

 

Is there ever a case whereby TWO hot water cylinders are fitted in a property?

 

My son has two hot water cylinders in his loft. IIRC they are connected in series. They were plumbed like that when he bought the place and I think it's just a height issue. Probably cheaper to get two standard off the shelf cylinders, than get a bespoke one made.

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48 minutes ago, PeterStarck said:

My son has two hot water cylinders in his loft. IIRC they are connected in series. They were plumbed like that when he bought the place and I think it's just a height issue. Probably cheaper to get two standard off the shelf cylinders, than get a bespoke one made.

 

Cheers. Vindication at last! :)

 

I'd still though have an issue as the CWS tank is so small.

 

At the mo when filling the (huge) bath and someone's had / having a shower I can run the 25gal CWS tank dry. You can't just open the taps with gay abandon but are on edge listening for the gurgling of pipes running dry!

 

Of course then there's no head left to act on the hot in the cylinder so that stops as well.

 

The plumbing here is like somebody has dropped a stack of copper from a great height. The pipes from the shower pump next to the cylinder for instance go over the top of the dormer in the ceiling.

 

The pipes for DHW go from the cylinder AROUND the perimeter of the dormer in the uninsulated crawl space. It's loss after loss.

 

Really it needs a service duct through the upstairs floor so I get the shortest distance between two points for everything.

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