[ailishfagan]

Hi, I'm interested in switching my heating system to a combi boiler system. Combi boilers seem to be used all over Europe and I like the idea of constant hot water supply. However trying to get information on combi boilers from plumbers of heating suppliers is proving difficult. They don't seem to be used that much in Dublin. I'm worrying is that because they don't work here with low pressure hard water??? Anybody got any experience with this? It'd be of much use. Thanks

[gary71]

Originally Posted by ailishfagan

Hi, I'm interested in switching my heating system to a combi boiler system. Combi boilers seem to be used all over Europe and I like the idea of constant hot water supply. However trying to get information on combi boilers from plumbers of heating suppliers is proving difficult. They don't seem to be used that much in Dublin. I'm worrying is that because they don't work here with low pressure hard water??? Anybody got any experience with this? It'd be of much use. Thanks

Lots of combis fitted in Dublin

Combis require a good mains water supply which is hard to find in Dublin, some installers will fit a break tank to store water then pump it to feed the combi, I'm not a fan of this method as I think if you have low mains then a combi isn't suitable.

If you have any specific questions then ask away.

[shane0007]

They are also not suitable if there is lime in your mains water.

[JohnnieK]

Good pressure, good flow rate is very important. Lime would have to be addressed if present.

[ailishfagan]

Thank you so much for this information. Our water pressure is really not that good but we were thinking of fitting a variable feed pump between the storage tank and boiler to help with this. Also for the lime we were going to install a water softener. These two products alone with prob cost in the region of 2k! Is it worth it? The idea of hot water really appeals to me. I spend a fortune on emersions heating water.

Thanks again for passing on your experience!

[antoinolachtnai]

According to the bylaws, you cannot fit a combi directly to the mains in Dublin. There are a bunch of reasons for this, good and bad, but those are the rules.

http://www.dublincity.ie/SiteCollect...egulations.pdf - see section 39 in particular.

The way you are proposing to do it seems fine according to the rules. However, you would want to be sure you have plenty of water storage in the attic. And as you say, it is an expensive project.

Why would you not put in a high quality, fast recovery hot water tank, with its own connection to the boiler? This will also give you plenty of hot water. It would certainly be cheaper than what you are describing. If you have a large house with more than one bathroom, it would give you a lot more hot water at peak times, if that is an issue.

You cannot install a water softener without the permission of the City Council.

http://www.dublincity.ie/SiteCollect...r_Bye-laws.pdf

Lots of people seem to ignore these bylaws and it probably works out fine, but these are the rules.

[gary71]

Originally Posted by antoinolachtnai

Lots of people seem to ignore these bylaws and it probably works out fine, but these are the rules.

rules are only as good as the inforcement, i have a site with over 500 38kw combi's mainly used by the council for housing, the council had a say at the design stage, so it would seem rules are of no concern, unfortunately.

[DGOBS]

That being the case, should not the city council then be held responsible for all the appliance damage done by the hard water they supply instead!

What GOOD reason is there for not fitting a combi?


And as for this one....

6. A person shall not, for conveying, delivering, receiving or using water supplied by the Corporation, fix, fit, or use or cause or permit to be fixed, fitted or used any pipe fitting or apparatus which shall not be of god quality and shall not be in accordance with such of the requirements hereinafter set forth as shall be applicable to it.

How the hell can I get a omnipotent quality fitting!

[antoinolachtnai]

A good reason for the consumer for not connecting a combi direct to the mains is that there is no guarantee of either pressure or supply. This means that a really bad thing could happen to your boiler.

Another good reason to avoid it is that the pressure might be inadequate in the upstairs part of the house even though it is fine downstairs. Another reason is that the flow of hot watermay not be enough for a house or apartment where two people bathe at the same time.

A good reason for the council to require cisterns is to reduce the peak load on the water network.

A good reason for the plumber not to install a combi would appear to be as follows. If you are a plumber and your customer has these or any other problems, you will be facing an expensive replacement. You won't be able to contest it because the work and the equipment isn't fit for purpose. Even if the homeowner or architect specified a combi boiler, you will still be the guy on the hook because you've broken the local bylaws, which it is your job to know. I don't know a case of this happening myself but it could easily happen.

All my opinion of course. I don't mean to discourage anybody!

[DGOBS]

I have loads of customers with combi boilers, all love them. The only downside is in event of a water cut there is no storage of water.

The only real reason you gave there is 'peak usage' all other revolve around correct installation of the appliance, kind of a non argument as the 'installer' will be the one responsible not the customer as the installer is deemed 'competent' not the customer.

Combi boilers are not suitable for every installation, usage, water pressure etc are all factors in the decision for/not for fitting a combi. Assuming your installation fits the criteria it is without a doubt one of the best, cost effective and efficient options on the market.

All my opinion of course.

[antoinolachtnai]

The problem for the installer (or plumber or whatever they arecalled) is that if there is a problem in the future, if the installation has not been done to code (ie the boiler has a direct connection to mains), the installer carries the full responsibility. An example of a problem might be that the water pressure falls in the area. It should not happen, but it could, and the householder has no comeback with the local authority.

It will work In most circumstances and will suit a lot of requirements for sure.

The OP has not given full details of how big their house is, but it does not sound like a great candidate for a combi to me.

[gary71]

Originally Posted by antoinolachtnai

The problem for the installer (or plumber or whatever they arecalled) is that if there is a problem in the future, if the installation has not been done to code (ie the boiler has a direct connection to mains), the installer carries the full responsibility. An example of a problem might be that the water pressure falls in the area. It should not happen, but it could, and the householder has no comeback with the local authority.

It will work In most circumstances and will suit a lot of requirements for sure.

The OP has not given full details of how big their house is, but it does not sound like a great candidate for a combi to me.

A installer takes a snap shot in time to decide on what is suitable and what is not, if you go by what you say then no sealed system, water heaters or unvented cylinders would be suitable due to possible future events, the OP wants to use a breaktank to deal with the pressure issues which would sort the connection to the mains issue.

[antoinolachtnai]

If your water authority is willing to guarantee pressure or is at least required by law to provide a certain pressure, and allows direct connections, that approach is absolutely correct.

What the OP proposes to do looks completely legal and workable. The problem with it is that it is a very expensive solution. It is also pretty noisy because it requires the whole water system to be pressurised with a pump in the attic. It seems to me that it would cost less for a good tank and a circuit from boiler to the hot water tank ( which need not be in an old style hot press). If done right, this will heat pretty fast. It will also be much cheaper than an immersion.

[DGOBS]

I really don't understand that argument, as combi boilers have flow switches, so it the water pressure is too low they won't fire. It's not like they are going to explode, worst case is they would lockout and require a reset!

[heinbloed]

The OP wrote:

Our water pressure is really not that good but we were thinking of fitting a variable feed pump between the storage tank and boiler to help with this

Find out why that is.
A frequent reason for meassuring low pressure at the house' mains is bad plumbing.
With the 'metered water' now rolling in there is a minimum pressure demanded, the consumption counters (amateurs say meters ) work only between a certain minimum and maximum pressure.
And this EU legislation will bring up the pressure at the counter. It is up to the competent plumber to install a plumbing system which shows low pressure losses.
A new pipe from the main supply/counter will be then the straight answer.

Also for the lime we were going to install a water softener.

There are combi-boilers which take (nearly)any hardness of water on the DHW side, only the amateurs will deny this.

Settlement of lime in a heated system happens mainly at over 60 or 65 degrees Celsius, the laws of physics....

Note that there are answerers to your question in this thread who have been told via this forum how a combi condensing boiler works only a year ago. And who claim to have seen 2 heatexchangers in their life time with a professional career of 30 years (so they say). Others recommend illegal DHW systems no problem. DGOBS isn't meant.

Employ a professional, the term "plumber" isn't protected. Any dud is allowed to work in this profession and advise.
Get a heating engineer in who will advise independantly for a fee and who will controll the installation finally decided for.

Get the energy demand calculated according to
EN 12831 or some other official standard. Without it you are playing lotto with your decisions. This ticket is expensive. You fell before into the cheap-and-easy trap:

I spend a fortune on emersions heating water.

Solar thermal DHW systems usually work cheaper than direct electric or fossile fueled ones. If chosen and installed correctly.


PS

The physical amateur frequently mixes-up the water mains

pressure

with delivered volume per minute.
Make sure you explain the problem correctly, i.e. with numbers,units.