Combination storage boiler - good idea?

Registered Yes, why, do you want a boiler installing by a real and competent GSR installer, as you cannot and never have fitted one
 
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I would advise against a storage combi. You might aswell just replace your existing combi with a system boiler and an open vent cylinder. I had nothing but problems with the last storage combi we installed so I may be biased though!

Combis, as stated, have their time and place which in my opinion is in a small flat or 2 bed house with 1 bathroom.

Anything larger and combis struggle to cope unless as the OP states, you all sign a treaty to only have the shower on and no one else is allowed to use the hot tap!

In my experience, all but the best plumbers will suggest fitting a combi. Not to save you money, but to save them time, money and hassle as opposed to supplying the correct appliance to their customer.

My advice for a large house would be a system boiler and an unvented cylinder everytime. If your house is fairly routine (i.e. everyone has a shower in the morning and a bath at night), you will be able to set the system up so you are only heating water for the amount of time needed.

The first thing to do however is to establish your incoming mains water flow and pressure. The easiest way to check your flow is to time how long it takes to fill a 10-litre bucket from your kitchen tap. Pressure is a little trickier, but if your house is fairly new you should have at least 1 bar.
 
I would advise against a storage combi. You might aswell just replace your existing combi with a system boiler and an open vent cylinder. I had nothing but problems with the last storage combi we installed so I may be biased though!

Combis, as stated, have their time and place which in my opinion is in a small flat or 2 bed house with 1 bathroom.

There are two bathroom combis around with some stored water models as well. Why should someone fit an expensive, inefficient space consuming system as you propose?

You should get yourself some exposure to the latest products on the market. If you are in the heating trade, not those plumbers that are mainly into drains, you owe it to yourself and your customers to get ahead with technology and the latest products. Separate cylinders and 3-way valve all over is just not needed in most British homes.

If the mains pipe can cope, a quality combi is the first line of attack when assessing a normal house. Anything bigger then a different view is needed.
 
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I admit that most of the work I do is associated with commercial/industrial work so I may not be fully up to speed on domestic products.

However some of the smaller sheds with offices at one end usually have the same number of appliances as a large house.

The only time we ever put combis in is if we are tight on price and want to do it cheaply & nastily.

Your arguement is utterly flawed as the OP has a combi, and it doesn't work in his house. :rolleyes:
 
I admit that most of the work I do is associated with commercial/industrial work so I may not be fully up to speed on domestic products.

Well a honest man, unlike some on this forum.

However some of the smaller sheds with offices at one end usually have the same number of appliances as a large house.

The only time we ever put combis in is if we are tight on price and want to do it cheaply & nastily.

Your arguement is utterly flawed as the OP has a combi, and it doesn't work in his house. :rolleyes:

My argument is not flawed. His combis is undersized and his water mains need uprating or a grundfos booster or an accumulator fitted to boost supply.

As to new high flow quality combis many are about.
Look at these:

Rinnai Twinflow:
http://www.rinnaiuk.com/Updates-18-09-08/A4 Twin Flow.pdf

ATAG Q51C 51kW combi with a 13 litre instant cylinder. DHW, 23.2 L/min. Stainless steel heat exchanger. 5 year warranty. ATAG are about the best.

The Twinflow is a Rinnai and an ATAG in one frame. Rinnai deliver the DHW instantly.

W-B 550 Highflow (floor mounted) 25 litres/min
Ethos 54C

The Remeha Avantaplus 39C combi.
Remeha have just bought Baxi, so the Baxi Heat Team will do the servicing soon when they get it all in place.

W-B 42kW

There are Glow Worm floor and wall mounted stored water combis - they are two stage DHW delivery. Usually around 13 litres/min when the tank is cool.

The Alpha CD 50 wall mounted

Etc
Etc

Look at the ATAG. It can deliver 1392 litres an hour. A cylinder would need to be huge and very expensive to compete with that DHW delivery.
 
But a combi still cant cope with demand from several draw offs at the same time no matter the flow rate.
20 min average recovery time from a properly installed 300 litre unvented cylinder.
I would in no way recommend a combi to anyone with several en suites and or showers abd kitchen and utility etc.
Does the building regs not have something on the type of system that should be fitted depending on house size and water use.
I have seen some builders getting by, by making one en suite an electric shower and then putting in a combi!
 
But a combi still cant cope with demand from several draw offs at the same time no matter the flow rate.

That is total nonsense.

20 min average recovery time from a properly installed 300 litre unvented cylinder.

20 mins? What size boiler are you using there? And what capacity coil?

< snip>

It is clear by your writing that you know little of this.
 

That's fair enough, and it sounds like you know your products. What does my head are the folk who think a combi is the answer no matter what and get so stuck in their ways they can't see past it.

You will find they are the ones who install cheap combis with poor flowrates. And do not pipe them up right with taps robbing others of flow & pressure.

Unfortunately the cowboys slap them in will-nilly. They have one 15mm cold mains pipe snake around a house and all cold taps and appliances off that including the combi. The combi is treated as another tap. Then people wonder why the whole system doesn't work right. Also, a mains pressure water setup, combi, unvented, thermal store, needs balancing, so a toilet does not rob the shower, etc. A dishwasher can take a few minutes to fill as it doesn't matter. This is rarely done and few ever think of it. Many mains pressure systems can be improved by putting in flow regulators on taps and appliances. Shower is king in domestic water setup and all should geared to keeping them with constant flow & pressure.

A well speced quality combi that is installed properly will last and last, and at the higher end do two bathrooms. They are a panacea if a simple heating system is wanted with no solar, etc. One box solution, with no having to match boilers and cylinders and do controls and valves. Most mismatch them leading to inefficiency. It kills many birds with one stone - but again it has to be quality, sized up right and fitted right.

Rinnai have the TwinFlow, an ATAG boiler and Rinnai multipoint in one frame. One gas pipe to them both as both will never be on at the same time. You can spec the size of the Rinnai multi-point. When DHW is called the CH boiler is switched out so gas consumption below the U6 meter capacity. You can adjust the temperature of a bath or shower inside the shower with a hand held remote-control waterproof unit. Just turn the shower mixer to full hot and adjust the temperature. Yep, all is there if you want it.

Body Jet showers and instant water heating are a perfect match. If you have two of them you will need a very large cylinder. And that will cost and cost.
 
you should really post a pic of the last one you fitted drivel :rolleyes:

This is the sort of non-constructive nonsense this forum is full of. More noise!!!

The admin should delete these cluttering posts that serve no purpose.
 

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