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damaan

Hello everyone,
I need to change my boiler and I am very confused. I don't know very much about boilers and which one is best for me and my family and so I decided to get several quote - very wise! I have a 4 bed 2 bathroom house with a conventional boiler and tank in an airing cupboard. It has 13 radiators in total and I am currently in the process of getting quotes for new bathrooms as they are very dated now. The boiler is old and so I thought to do the boiler first so that it gave me more flexibility with power showers for the new bathrooms. There are 4/5 people in the house (son is at Uni), but we never take 2 showers at the same time.
First heating engineer. Said to go for a unvented boiler system. Said it would be expensive and needs to be fitted by a specialist.
Second heating engineer. Said to go for a large combi boiler with either a combistore or Flue Gas Heat Recovery Device fitted. Again expensive but will save money in the long run.
Third heating engineer. Measured the flow rate of my water (15L/min or 12L/min at 1.5bar) and said to go for a conventional condensate boiler and install a larger tank in the airing cupboard. Again expensive because of the changes to boiler and tank.
I am now even more confused than before. I have been in this house for 15 years and have had rubbish showers because the water is gravity fed. I just want my new bathrooms to have decent showers with hot water and pressure.
Any advice would be welcomed.
Thanks.:(
 
if your cold water pressure is really good go for an unvented cylinder system
 
Thanks for the reply. How can I measure the pressure? One of the heating engineers measured a flow rate of 12L/min at 1.5bar - is this good? He was not impressed however!


if your cold water pressure is really good go for an unvented cylinder system
 
All of them are correct. But it's all about how much flow rate your house has. You can get a brilliant boiler and pressurised cylinder fitted. Or a good storage combi boiler. But you will still have 15litres a minute.
If you had a good flow rate, I would go for one of the above. But you haven't.
In my opinion, if you want good showers you could do one of the following.
1 whole house booster pump. With new boiler and pressurised cylinder.
Pros.. You can get as much flow as you need. Sky's the limit.
Cons. Costly and takes up space.
2. Larger hot water cylinder and inststall a good quality shower pump to feed showers.and new system boiler.
Pros... Good flow rate to showers and not much adaption of your current pipework.
Cons. Shower pumps can be noisy.
3. New 32kw combi boiler and remove existing cylinder.
Pros... Cheapest to install. Sole to maintain.
Cons. Only 12litres a minute ( but if your only using one hot outlet at once, will cope quite well)
If there is a fault with the boiler, there is no backup.

ive probably confused you more now!!
 
Welcome along

Right, all modern boilers are condensing boilers.
At the mo I would say your incoming mains is not suitable for an unvented cylinder.
Have any of the plumbers mentioned upgrading your mains to improve flow/pressure
I would not recommend a combi to run two bathrooms. Whilst you don't shower at the same time it can be affected by other outlets being open and to be fair it's not designed for what you want.
If you're not looking at the expense of upgrading your mains then I'd stick with the conventional heat only boiler with a vented cylinder. You could then look at the option of a shower or whole house pump to improve your shower experience
 
Thanks for the reply. How can I measure the pressure? One of the heating engineers measured a flow rate of 12L/min at 1.5bar - is this good? He was not impressed however!
12lpm is not good.
 
as above but to add if you could phone the water board up and ask them whats the pressure and flow rate in your street / area and if this is alot higher than your getting now might be worth looking to upgrade your water main with something like a 25-32mm alk
 
I have just spoken to Severn Trent water who have said 12L/min at 1.5bar pressure is very good!
Also, I have just checked the external stop-cock to my house(situated just outside my house on the pavement). This stop-cock is not fully open - it is only half open - will this affect pressure and flow rate? Also, if I open this, could this cause a surge in pressure and hence could cause a leak in my system?
Thanks.


as above but to add if you could phone the water board up and ask them whats the pressure and flow rate in your street / area and if this is alot higher than your getting now might be worth looking to upgrade your water main with something like a 25-32mm alk
 
I have just spoken to Severn Trent water who have said 12L/min at 1.5bar pressure is very good!
Also, I have just checked the external stop-cock to my house(situated just outside my house on the pavement). This stop-cock is not fully open - it is only half open - will this affect pressure and flow rate? Also, if I open this, could this cause a surge in pressure and hence could cause a leak in my system?
Thanks.

Yes will effect the flow rate abit open it up and re test and come back to us
 
I have just opened the tap and I have a new flow rate of about 20L/min. Does this new flow rate make a difference to which boiler system would be best?
Thanks to all.




Yes will effect the flow rate abit open it up and re test and come back to us
 
In your situation I would go unvented cylinder all the way. Just need to get a couple of quotes to that affect. Make sure the engineers are G3 qualified
 
I have just opened the tap and I have a new flow rate of about 20L/min. Does this new flow rate make a difference to which boiler system would be best?

Thanks to all.

At 20 l/min it's suitable for an unvented cylinder which would give you excellent showers, more than one outlet usable at a time, immersion heater(s) as a backup if the boiler packs up, etc. It's not THAT expensive in context of having bathrooms etc, done.

I would avoid using the plumber who tested at 12/15l/min and didn't think to check the outside stop tap. I'd also avoid using those who didn't check at all!
 
At 20 l/min it's suitable for an unvented cylinder which would give you excellent showers, more than one outlet usable at a time, immersion heater(s) as a backup if the boiler packs up, etc. It's not THAT expensive in context of having bathrooms etc, done.

I would avoid using the plumber who tested at 12/15l/min and didn't think to check the outside stop tap. I'd also avoid using those who didn't check at all!

I think he was the only one to test
 
I have just opened the tap and I have a new flow rate of about 20L/min. Does this new flow rate make a difference to which boiler system would be best?
Thanks to all.

What tap did you test from? Most taps have now something that will restrict the flow and give a false flow reading. Some outside taps have check valves inside them, plus the hose nozzle will restrict flow greatly. Also the pipe feeding the tap might have an isolating valve on it and if it is a slotted screw isolator then it highly likely is small flow type.
 
Rechecked with somebody else (same tap) and got 17/18 lpm. Anybody has any idea of the figure I am looking at if I want to change to UNVENTED system? People have been saying ÂŁ10000???? Is it such a big job? Wife worried about risk of failure with explosion....
 
It is very difficult to comment on the price without seeing the job but if these things are installed properly by a qualified person then you don't have anything to worry about
 
I have just come across this thread, don't know if the OP is sorted yet? I thought a system boiler with a thermal store may be suitable? Gledhill and Chelmer produce a variety of units. Installation would be less expensive than an unvented system, no risk of explosion and lower maintenance costs going forward, plus good hot water flow rates.
 
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Thermal stores are unvented with the same requirements for their installation and maintenance.

And would be overkill for this job.
 
Thermal store for multiple heat sources otherwise an expensive option to maintain the higher temps required to generate hot water.
 
I think the OP is put in the same position as many users. Who to trust and what's the yardstick to judge by. So let's see if we can give him a check list on how to choose an installer. I am not a heating engineer but when I am choosing an installer or any trade to work for me I want these in no particular order?

Do they have the correct qualification for the job, in this case G3 cert.?
Do they have a provable track record of satisfied customers I can call and visit and a rep they don't want to lose?
Do I want these people in my home, are they going to respect me and my home?
Do they have, and can supply proof of, sufficient public liability insurance?
Are they able to provide a maintenance program, annual G3 service, etc?
Can they do the work within an acceptable time period, even a guaranteed time period?


I am sure other more qualified will be along to add more to the list.

With regard to price, I just had a new boiler and 6 ft high Megaflow installed in a 10 year old house, which has 3 bathrooms, 13 rads, underfloor heating in a 5 X 10 meter extension, it involved removing pumps from 2 bathrooms and removing cws, and a very complicated plumbing of the pressure relief. This was done by a father and son team who I have known for years and do lots of work for me, long waiting list, very reliable. In and out in 2.5 days, all nice and clean, waste removed, power flush etc etc, ÂŁ6000 inc vat
 
Go for a conventional system boiler, upgrade the cylinder and fit Trevi boost showers as the mains pressure boosts flow of the hot water. No electrics needed and quite (no noisy shower pump).
 
Go for a conventional system boiler, upgrade the cylinder and fit Trevi boost showers as the mains pressure boosts flow of the hot water. No electrics needed and quite (no noisy shower pump).

Ancient post pal !!
 
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