Megaflow or Combi???????

[kevplumb]

PostPosted: Mon Apr 17, 2006 3:24 pm Post Subject:

could always start a new thread this one is three years old

 

[doitall]

You could have a combi doing the kitchen/utility and water heaters doing the bathrooms.

But the big problem will be can the mains supply it it.

You need to get the incoming mains pressure and flow rate checked before deciding on anything.

 

[Handyman]

Megaflow (or similar) every time for anything larger than a retirement bungalow. Each of my 3 kids have combis (and 2 children) and their systems are rubbish: low HW flow rates, inconsistent temperature, wasting loads of water waiting for the hot to come through, physically large size of boiler, etc. Several of my customers have also complained of limitations that their new combis have presented which were not clearly explained by the fitters.

Try and position the tank as near as possible to the kitchen sink. We get hot water within 3or4 seconds from ours. Our 210L tank heats up from cold in about 20 mins and can keep pace with continuous showers when all the family are around. Ours is a "Range Tribune" and most of the new pipework is 22mm to ensure maximum flow to shower, bath, etc.

But definitely check mains flow capacity first.

 

[GeorgeBramwell]

hi,
i need help with a similar problem..

getting a loft conversion so the house will be 3 floors with 6 bedrooms and one bathroom on each floor.
really unsure of whether to go for a combi or megaflow. i hear the combi has limited flow rates but could it be possible to install two? (one for upstairs and downstairs...)
or should i go with megaflow? seems like this may be the most expensive option because we'd have to change a lot of the pipes around the house and from the mains water supply ..(something to do with pressure that i didnt understand!)

any suggestions? thanks!

Large flowrate combis beat cylinders hands down for DHW delivery. See thread: //www.diynot.com/forums/viewtopic.php?t=193040

You have to assess if all three baths will be filling at the same time. Any system will slow up when this happens. If you want three baths filling fast you will be looking at a small commercial system. In most houses two baths filling at the same time is very rare. Two showers at the same time is more common. So, some common sense has to be applied to usage.

OK two showers may be running at the same time. I would seriously consider as first option, depending on your usage, a high flowrate quality combi. Look at the ATAG, W-Bosch floor mounted 550 Highflow (can go in the garage space), Ethos 54kW (this can have secondary circulation DHW loop to give instant DHW at the taps) All these are 25/26 litres/min. Most cold water mains pipes deliver around 30 litres/min, so an expensive unvented cylinder cannot do any better as it will only give you around 25 litres/min. Your limitation is the cold water pipe.

These combis will deliver the flows and the most cost effective route. The cylinders and tanks are removed saving space and potential problems.

An unvented cylinder needs an annual service which costs, so avoid.

Check the flowrate in litres/min and pressure in bar of your cold mains pipe and get back.

 

[GeorgeBramwell]

Megaflow (or similar) every time for anything larger than a retirement bungalow. Each of my 3 kids have combis (and 2 children) and their systems are rubbish: low HW flow rates,

You are obviously a DIYer/handyman. Read my other posts.

 

[kevplumb]

These combis will deliver the flows and the most cost effective route. The cylinders and tanks are removed saving space and potential problems.

exept repair bills combi's break down more tha cylinders

An unvented cylinder needs an annual service which costs, so avoid.

so does a combi

 

[corgikiller666]

georgebumwell is clearly a muppet who hasn't a clue, take his advice with a large pinch of salt.

 

[kevindgas]

georgebumwell is clearly a muppet who hasn't a clue, take his advice with a large pinch of salt.

or just ignore him

 

[GeorgeBramwell]

These combis will deliver the flows and the most cost effective route. The cylinders and tanks are removed saving space and potential problems.

exept repair bills combi's break down more tha cylinders

How would you know? They don't have combis is the USA, especially in redneckland.

Quality combis break down no more than a quality boiler. Get it?

An unvented cylinder needs an annual service which costs, so avoid.

so does a combi

But only one service. A boiler a unvented cylinder is two services. Two annual charges. Get it? easy isn't it? You may get there one day.

 

[GeorgeBramwell]

georgebumwell is clearly a muppet who hasn't a clue, take his advice with a large pinch of salt.

Point me to what you don't understand. I will help you along.

 

[kevplumb]

How would you know? They don't have combis is the USA, especially in redneckland.

wrong again muppet if you want to start hurling abuse get your facts right

 

[corgikiller666]

georgebumwell is clearly a muppet who hasn't a clue, take his advice with a large pinch of salt.

Point me to what you don't understand. I will help you along.

I don't understand why you pretend to be an expert when you clearly are not, nor do I understand why you deny being yet another reincarnation of bigburner/drdrivel etc etc.

You are clearly a byproduct of the failings in mental health provision in the nhs and for that I feel very sorry for you.

 

[Handyman]

Now, now. Calm down, girls.

George B'well is correct in one respect. I might not be a fully qualified plumber, but I happen to have a lot of customers who have been misled into the perceived benefits of combis, resulting in me modifying things to give the customer what he/she wants (e.g. an airing cupboard that works, re-routing pipes to improve hot water delivery, getting my own tame plumber to reposition the boiler in a more sensible location, and even getting the customer's plumber back to install the boiler correctly).

I also have a highly efficient high-pressure HW/CH system designed and installed by myself (not the boiler, though) which is more practically designed and more efficient that any other combi system I have come across. I used 22mm pipe throughout (apart from WC and basin tap connections) including upgrading the incoming mains to 22mm. Flow rate is certainly not a problem. Yes, it was considerably more expensive, but I would never go back to a 'tank in the loft' or 'combi' system.

I get the impression that plumbers down here recommend combis because they are easiest to install when someone wants a new boiler, rather than finding out what the customer really needs for their lifestyle.

I appreciate that it's horses for courses and no two installations are the same, but I based my recommendation to mlh07 on my experience with the practical needs of my (many) customers.

If mlh07 really wants to push the boat out, he might like to consider the even more expensive option of a Megaflow type system with a dual coil, with the second coil connected to solar panels......

 

[GeorgeBramwell]

I get the impression that plumbers down here recommend combis because they are easiest to install when someone wants a new boiler, rather than finding out what the customer really needs for their lifestyle.

You have to know what is on the market. High flow quality combis are very cost effective and do away with unvented cylinder, or cylinders or any kind. Few know of these superb products and fit inappropriately combis. I usually go the combi option as the first line of attack.

Where the main water flow was poor I have found it cost effective to install a cold water accumulator and high flow combi. Customers are delighted with performance.

 

[corgikiller666]

I get the impression that plumbers down here recommend combis because they are easiest to install when someone wants a new boiler, rather than finding out what the customer really needs for their lifestyle.

You have to know what is on he market. High flow quality combis are very cost effective and do away with unvented cylinder, or cylinders or any kind. Few know of these superb products. I usually go the combis option as the first line of attack.

Where the main water flow was poor I have found it cost effective to install a cold water accumulator and high flow combi. Customers are delighted with performance.

georgebumwell have you got any customer references we can check? are you gas safe registered or qualified in any way?