Replacement UV cylinder

[fezster]

As the kids are growing, I'm finding our 250L Megaflo is occasionally running out of HW.

What are opinions on having a second UV cylinder vs having a bigger 400/500L cylinder fitted? Any pros and cons?

My Megaflo is "only" 7 years old. Is there any resale value to these things, or do I just have to have it gotten rid of?

And in terms of brand - seems the Joule is recommended. Any others to consider?

 

[Scott_D]

How many showers and for how long approximately?
Set the hot water times so it’s up to temp before demand and on during times of use.
You could try adding a circulation pump to get the full 250l at 65 degrees

 

[SJB060685]

If theres space why not just add a second in parallel, saves getting rid of your current one

 

[fezster]

How many showers and for how long approximately?
Set the hot water times so it’s up to temp before demand and on during times of use.
You could try adding a circulation pump to get the full 250l at 65 degrees

Max 2 showers at once, but they are quite a high flow rate (15-20 L/min). The cylinder is set to heat up before the heating comes on. It also heats up whilst the heating is on, but I'd imagine the flow temps are substantially lower due to heating demand.

I hadn't considered de-stratifying - is that something often done on unvented cylinders?
[automerge]1583505436[/automerge]

If theres space why not just add a second in parallel, saves getting rid of your current one

That's what Im thinking, but wanted to know if there was any significant downside. I suppose one being 2 cylinders to maintain and heat. Wondering if I should just bite the bullet and put a single 400/500L in.

 

[ShaunCorbs]

whats your hot water times might be worth leaving them on 24/7 worth a try?

 

[EvilDrPorkChop]

HW priority, can be simply done with a relay. Our 170l reheats recovers 15 minutes quicker when used. What size is your boiler output as your coil will be rated at 24kw in that MegaFlo.

You shouldn't really be running out much with a 250l even at them flow rates. We have a 170l MegaFlo (Inherited, HW stored at 55), our showers are around 16/17lpm, at two 10 minute showers (@40oc) we can just about get enough HW out of it for them.

Is it better in summer when the CH isn't on?

 

[fezster]

Boiler is a Vaillant 438.

I'm not sure about in Summer, but I guess will find out soon enough. The kids are only just now using the shower more excessively. I will have to educate them on how HW can run out and not to spend unnecessarily long in there.

I'm toying with the HW priority and increased cylinder temp (with blending valve) - as advised on another forum. I think I'll wait to replace the cylinder with one larger one as and when this becomes a bigger problem, rather than having a second cylinder fitted which seems far more costlier/complicated.

 

[ShaunCorbs]

I wouldn’t increase your store temp as this can lead to other problems as the cylinder isn’t designed for this

 

[EvilDrPorkChop]

Boiler is a Vaillant 438.

I'm not sure about in Summer, but I guess will find out soon enough. The kids are only just now using the shower more excessively. I will have to educate them on how HW can run out and not to spend unnecessarily long in there.

I'm toying with the HW priority and increased cylinder temp (with blending valve) - as advised on another forum. I think I'll wait to replace the cylinder with one larger one as and when this becomes a bigger problem, rather than having a second cylinder fitted which seems far more costlier/complicated.

I think the blending valve is OTT, storing at 60oc is more than enough. I wouldn't want to be storing it any higher as Shaun says.

You'd be surprised how much HW priority helps.

 

[fezster]

Thanks all. I wont go down the blending valve route having looked into what problems increasing temp causes. Thanks for pointing that out.

 

[Scott_D]

Have you done some basic test with a thermometer and stop watch.
Minutes used, litres per min of outlets and temp drop!

 

[king of pipes]

Just add flow limiters to the showers 8 litres a minute is enough for a good shower saves water and you money . Kop