Plumber says I can have unvented @ 13lpm ?

[hard-work]

The Intergas is 13 litre per min. But, the DHW temperature can be set to 65C by the user. Too hot for taps. But, have a blending valve set to 45-50C supplying all the taps except the two showers. What this means is that the hotter the water to the mixer the more cold water will be needed to get the required 42-45C mixed at the shower valve. Thermostatic mixer valves as essential.

You may want to fit wondervalves at the kitchen sink outlets with a 6 litre cartridge in each. On the basins have a lower litres cartridges like 4 litres. Then when these taps are turn on they will reduce influence on the shower(s), by not stealing pressure and flow. And also reduce water usage reducing bills.

 

[hard-work]

ok, this is our shower head :-

https://www.victorianplumbing.co.uk/belmont-traditional-8-apron-rose-shower-head-with-swivel-joint

We do like a decent shower but don't expect a monsoon - will a combi or unvented cylinder service this shower head ok ?

Get one of these at 9 litres per min, but aerated.

https://www.xtwostore.co.uk/hansgro...kv7x6qthRpRwxqYjWwVU8ZNTY4o91qHhoC6asQAvD_BwE

Gives a big shower feeling but with less water. And hence less bills in gas an water. It will work nice even with the Belmont mixer. The Belmont head is not that good with a high flowrate.

 

[John D v2.0]

Hansgrohe Rainfall shower heads are aerate and deliverer 9 litre per min. Keep water bills down as well.

Agree with that, we are fitting a grohe and the water usage claims to be very good.
I don't agree that it's necessary to heat water in a Combi to 65 for a shower, you only need 40c even if you're cold blooded! So heat it to what you need not higher as it's wasteful

 

[hard-work]

Agree with that, we are fitting a grohe and the water usage claims to be very good.
I don't agree that it's necessary to heat water in a Combi to 65 for a shower, you only need 40c even if you're cold blooded! So heat it to what you need not higher as it's wasteful

Get what I am on about. If there is a cold mains flow of 13 litre per min, and you want to use two showers, the two Rainfall showers at 18 litres min total with a combi say at 16 litres min will deliver enough hot water to the showers to have both reduced but operational. One shower will of course be fine. The hotter the water the less hot water volume you will need, as the cold water will make it up. In winter a 13 litres per min shower will not deliver 13 litres, they deliverer a hell of a lot less, so a combi that is rated at 35c temp rise giving 13 litres per min will give less in winter, so a combi rated at 16 litres per min will deliver no matter what season. When freezing outside, a 16 litre per min shower will still be working flat out with a 13 litres per min main flowrate. In summer it will most probably modulate down.

 

[John D v2.0]

I'm not sure if your terminology just differs but i get the gist i think.
Boilers are rated on heat input in kw not on water flow rate.
Incoming water temperature changes and water flow rate changes will cause the boiler to adjust its heat input accordingly.
A boiler that does 50c rise at 9l per minute can do slightly more than 25c rise at 18l per minute due to condensing better.
Agree some boiler can include a flow restrictor on the water input but can sometimes be removed. Also the pipe work from the boiler may be undersized therefore restricting the flow.
Anyway, the OP only has 13l in total at 1 bar residual.

 

[wwwebber]

Combi it is then. Look at the Intergas ECO RF 36

I was quoted £1200 for a megaflow unvented cylinder. Could this Intergas Combi be installed for a similar amount ?

 

[Dan Robinson]

Not properly.

I'd be surprised if a megaflow could be either, but, we've not seen the job.

 

[muggles]

I was quoted £1200 for a megaflow unvented cylinder. Could this Intergas Combi be installed for a similar amount ?

If it was a true Megaflo, IE that brand rather than a generic term (think hoover vs Hoover) then £1200 all in sounds way too cheap for a proper job to be done. The cylinder alone is circa £1050, so he's leaving £150 for labour and materials. No way a proper job is going to be done for that money. Might explain why he thinks your mains performance is sufficient for an unvented cylinder as well - he's a muppet who most likely isn't actually qualified and G3 registered to fit unvented cylinders.

Returning to your question, no you're unlikely to get a decent job on a combi install for £1200 either. Pay peanuts, get monkeys

 

[hard-work]

Another economical solution to only 13 litre min mains flow.

• Have a combi that does the showers only, to give high pressure, the only outlets you need high pressure;
• The combi heats one of these to supply all the hot & cold taps;
• The drinking tap in the kitchen is also off the cold mains;
• Cold taps taken from the tank in the top half of the cylinder, including toilet, washing machine, etc;
• No tanks in the loft;
• No unvented cylinder;
• Excellent low pressure flows to the bath;
• No annual charge for service;
• No explosion risk;
• Safe low pressure;
• Very fast heat recovery if a large kW coil is fitted as it will take approx 28kW from the combi;
• Could have the kitchen hot tap off the combi, if mains good enough. Then the cylinder is used mainly just for the baths;
• No air cushion to recharge;
• Service free;
• Use tundish and have the overflow into the drain stack, so no penetration of outside wall.

1950 Height / 500 Diameter / 190-120 L Capacity
http://www.heatmerchants.ie/page/kingspan/174

This company will make any size for you:
http://www.newarkcoppercylinder.co....rs--hot-and-cold-water-storage-cylinders.html

 

[John D v2.0]

I'm prone to overcomplicating things but that seems even more. If you really want an atmospheric tank why not just use that for the shower? You can easily pump it.
Or swap the tank for an accumulator and lose the stored hw.
Just seems no point having the complexity of both!

 

[muggles]

Hard-work by name, hard-work by nature - an over-complicated "solution" to a simple problem

 

[hard-work]

John D, A pump? Forget those. Noise and vibration, and prone to leaks unless you spend a fortune for one. They will leak eventually, they always do.

e.g.:

• an Intergas Rapid combi sized for the shower and kitchen tap for fresh and high pressure water;
• The shower never runs out, delivering say 390 litres of hot water in 30 mins;
• A combination cylinder of 100 litres of hot and 100 litres of cold;
• It can have the plastic cladding around the cylinder;
• The size of one of these is only slightly taller than an unvented cylinder;
• All in one unit;
• The low pressure benefits are as above;
• No tank in the loft;
• It delivers the same as an unvented cylinder mains hot and cold system;
• Cheaper to run as only heated for baths;

I believe these are popular in Dublin reading on the web, made by Kingspan, as the water mains is generally poor in that that city.

 

[hard-work]

Hard-work by name, hard-work by nature - an over-complicated "solution" to a simple problem

It is actually a very simple solution, and probably much cheaper as well, to a problem of poor mains flow, as the city of Dublin found out.

• High pressure shower(s) via the combi;
• All in one unit. Pipe up like an unvented cylinder (most unvented have the cold outlets coming off it, as this does);
• Cylinder at low pressure;
• No power shower pumps;

 

[bernardgreen]

It is actually a very simple solution, and probably much cheaper as well, to a problem of poor mains flow, as the city of Dublin found out.

• High pressure shower(s) via the combi;

If there is poor mains flow then the choice of which combi is restricted to those combi boilers that are happy with poor mains flow.

A very very simple solution is

A simple system boiler
A cylinder with second coil at top for heating water from mains to the shower
A cold water cistern a couple of feet above the cylinder to replace water drawn from the cylinder for sinks, basins, baths etc etc .

Most plumbers no longer do simple

EDIT More accurate :- Most plumbers on this forum no longer do simple

 

[Dan Robinson]

Yaaaaaaaaaaaaawwwwwwwwwwwwwwwwwwwnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn.