Combination boiler in a 4 bed semi

cyclonebri1

daveyjp wrote: »

If a registered gas installer has said a combi is suitable for a four bed four person household with two showers find another installer.

Can't agree more.

I'm a user not an installer, I have had a glow worm swiftflow 100e combi heating my 4 double bed detached dormer bungalow for 17 years. I boiler shower and 1 electric.

This year I decided to replace to "near future proof" the home if you get that.

I went with exactly the same type of boiler but this 1 of course is condensing, the earlier 1 isn't.

Points of fact; the earlier boiler did experience a small drop in temp if the shower was used and then the taps turned on elsewhere.
The new 1 shows no such affect, the kitchen tap and the wash basin don't affect it.

Would a 2nd shower on the same system work?

Well no, it wont, go for 1 shower on the combi system and for the odd occasion when 2 showers are being used at the same time, go electric for No 2. Use No1 as the main unit.

Thew heating won't work when using the shower , the tap, the bath????

Well no, it won't, water gets priority over heating, also gets more input from gas. But just ask yourself if you think you will notice a temp drop in the house whilst you take a shower or even a bath?

I don't need to suggest an answer.;);)

daveyjp

As you are still looking I would get a list of questions and sit down with your installer and discuss your options based on your requirements and a survey - the key to a combi is water pressure.

I notice you mention a 42cdi in another thread. This is far removed from a 29cdi and whilst it does deliver lots of hot water, this is only any good if your water pressure is high enough.

That's why a proper survey is essential. No point spending £1500 on a 42cdi (and the running costs associated with a high output boiler) if your water pressure is too low for it to operate a max output.

There is a third way. A combi which has a hot water storage tank so you get 20-30 litres of hot water stored on board - in essence a mini megaflow. Vaillant Ecotec Plus 937 is one such boiler.

lstar337

FEDEX wrote: »

Do you have a ball park figure for putting in an electrical shower?

Sorry, not an installer.

You will need a cold feed and the shower itself. Showers are anywhere from £50 - £350 depending on the model.

cyclonebri1 probably has the best Idea, get a combi spec for a single shower and get a single electric shower to use when the main shower is occupied. That way you have the use of an economical gas shower without having to pay out for a colossal boiler for the odd occasion when two people need to shower at the same time.

We have a combi (Ideal Logic+) and a thermostatic shower and I have never noticed a drop in temperature when my OH uses the wash basin. Running the hot full on another tap might be an issue, depends how often that is likely to happen.

sam1970

sorry as I dont mean to hijack the thread but it is very interesting to me....we currently have traditional central heating (the one with alot of stuff in the loft) and we are planning loft conversion so was thinking combi. It is a 4 bed detached house so what pepole are thinking of combi? and what is the unvented cylinder system? does it need installation in the loft? I will be very grateful for advice

Waterlily24

We have a combi boiler in a four bedroom/ 3 bathroom house and it is fine, only two people here most of the time but most weekend there are four or five. We haven't had any problems apart from the hot water taking quite a long time to come through sometimes. It is an oil boiler and we had a larger one than first advised.

ds1980

Never heard such nonsense. I have 5 bed 3 bathroom 3 storey house. I turn the hot tap on and hey presto hot water. I have 3 thermostatic showers, 1 bath, 5 sinks & 2 outside taps.

Don't understand people that seem to think cylinders are the best thing since sliced bread. When realistically are all these going to be used at the same time? Even when i am the bath still fills with hot water, the showers still run without the need for you to run around in it and people can still wash their teeth.

My gas bill for the 3 months this summer was £15. Yep £15 i can post a pic if you want. I have a gas hob also.

I have 8 or 9 rads and 3 towels rads. Ill be adding 2/3 more rads in an extension soon and it'll all run off the same boiler without problems or incident I'm sure. P.S. its a Vaillant 837 so not massive.

Any registered gas fitter that "tells" a customer a load of nonsense shouldn't be in the job. Don't believe the hype. Forgot to mention....they're probably the same ones that say you need a "powerflush"!

FEDEX

ds1980 wrote: »

Never heard such nonsense. I have 5 bed 3 bathroom 3 storey house. I turn the hot tap on and hey presto hot water. I have 3 thermostatic showers, 1 bath, 5 sinks & 2 outside taps.

Don't understand people that seem to think cylinders are the best thing since sliced bread. When realistically are all these going to be used at the same time? Even when i am the bath still fills with hot water, the showers still run without the need for you to run around in it and people can still wash their teeth.

My gas bill for the 3 months this summer was £15. Yep £15 i can post a pic if you want. I have a gas hob also.

I have 8 or 9 rads and 3 towels rads. Ill be adding 2/3 more rads in an extension soon and it'll all run off the same boiler without problems or incident I'm sure. P.S. its a Vaillant 837 so not massive.

Any registered gas fitter that "tells" a customer a load of nonsense shouldn't be in the job. Don't believe the hype. Forgot to mention....they're probably the same ones that say you need a "powerflush"!

Haysuse!

You are smashing all conventional wisdom, and destroying any semblance of an argument or rationale I was building for a Megaflo.

I got a similar statement off another forum:

"I will probably be going against the grain on here. I have a large house that has about 12 rooms and a large hallway. I have 3 bathrooms (2 showers) and 17 rads. I have a combi (Baxi Duo Tec 40 HE) - this was my first ever combi and I have previously had normal heating systems with a hot water tank and a megaflow system.

This is the best system that I have used and am delighted with it. Granted if I am in the shower and the washing mashine is on and someone flushes the toilets you will feel the pressure drop. However, it is just a pressure drop, the temperature of the water has never ever altered.

I think we are lucky in that according to the last plumber that serviced my boiler the key to a combi working well is reasonably good mains pressure. The power I get from my combi showers is as good as the megaflow system but the real benefit is that it is the most efficient system that I have ever run and I have hot water whenever I want. The megaflow at the end of the day is a cylinder that runs out of water.

Not by design but we tend to run appliances such as washing machines and dishwashers when we are up and about and not when we are showering and we rarely find a situation where both showers are running at once. There may be some slight adjustments such as those that people may need to make for a combi to work, but I firmly believe it is worth making those adjustments for the benefits that it offers.

Just my opinion and as I say there will be many on here that disagree with what I have said here, but it works for me."

So, you know, the funny thing is, I have hardly ever heard anyone say, "You know, I got this system, and it was a let down, I recommend you get something else".

What does this mean?

Perhaps that most people make do and find happiness with whatever they buy.

And perhaps.... that....

Both Combis and Megaflos can work in 4 beds and bigger?

ds1980

firstly im certainly no expert and have ridiculous mains pressure tbh. I only have the stop !!!! on a quarter turn. My views are based on ive either done it, have it or seen it first hand generally. Ive only ever had combis when growing up and in dozens of houses ive owned/lived in over the years. Never had an issue except recently but that was a boiler fault not anything else. Im sure there are good reasons to choose a cylinder or whatever but to completely shun them seems like nonsense to me. As you can see i live with one in a situation everyone seems to tell me is not possible so you can make your own mind up. I also fitted all the pipework, rads etc myself which i was told wasn't the best idea but 6 years in everything still works and never had a leak. The powerflush comment is the same, most people will say youll need one but again that's generally nonsense based on my experience (nothing else). I've never had one on any boiler ive ever had installed on any properties and never had an issue. Again there's probably a need in certain jobs but nowhere near as many that seem to get done or i hear about it seems. Find someone you trust, get a price you are happy with and do as they say but im always cautious over things thatll cost me more money and i cant find conclusive evidence of it being required.

FEDEX

ds1980 wrote: »

firstly im certainly no expert and have ridiculous mains pressure tbh. I only have the stop !!!! on a quarter turn. My views are based on ive either done it, have it or seen it first hand generally. Ive only ever had combis when growing up and in dozens of houses ive owned/lived in over the years. Never had an issue except recently but that was a boiler fault not anything else. Im sure there are good reasons to choose a cylinder or whatever but to completely shun them seems like nonsense to me. As you can see i live with one in a situation everyone seems to tell me is not possible so you can make your own mind up. I also fitted all the pipework, rads etc myself which i was told wasn't the best idea but 6 years in everything still works and never had a leak. The powerflush comment is the same, most people will say youll need one but again that's generally nonsense based on my experience (nothing else). I've never had one on any boiler ive ever had installed on any properties and never had an issue. Again there's probably a need in certain jobs but nowhere near as many that seem to get done or i hear about it seems. Find someone you trust, get a price you are happy with and do as they say but im always cautious over things thatll cost me more money and i cant find conclusive evidence of it being required.

Fair point, you're someone who thinks for yourself, which slightly goes against the advice of trusting someone!

But perhaps like you I like to look it at two ways simultaneously.

What is everyone saying to me needs to be done? Its important to listen to people, and encourage them to express themselves, because they have a lot of experience.

And then, when you've collected what everyone has to say, you need to separate the wheat from the chaff.

I can see you've done that in a big way, I wouldn't mind re plumbing my house too, but I'm not really in a position to do that.

daveyjp

Common theme in both those threads is high mains pressure. A pressure test will be the decider.

Vaillant 937 and Baxi 40 HE are both very high output boilers, the largest the manufacturers produce for domestic installations.