New Central heating but problems, Please help

[Gasinspect]

Beginning to lose patience with this one, loads of good advice been given, take it!
First option, upgrade cold mains from stop tap to boiler. If still not enough, and you will always struggle to have two outlets at same time with combi in the loft, then you could have megaflo for second bathroom with diverter valve off combi heating side. Increase main from boundary into house to 25mm.

 

[Dale Sanders]

Yes I will upgrade to 22mm pipe.
I carried my question on to ask about the shower and it's the first I've heard about a megaflo so now it confused things even more as so many different things. First I'm being told I can't have a boost for flow now I'm being told I can

 

[Harvest Fields]

Yes I will upgrade to 22mm pipe.
I carried my question on to ask about the shower and it's the first I've heard about a megaflo so now it confused things even more as so many different things. First I'm being told I can't have a boost for flow now I'm being told I can

Mega flow is an unvented cylinder.

 

[Dale Sanders]

So I can add that to my current combi boiler?

 

[Vee]

yes.

 

[Dale Sanders]

Hi. I have been reccommded to install a salamander home boost. Thoughts?

 

[Harvest Fields]

Never fitted one but I have heard stories where the pipe to the house is not big enough to supply the demand that the pump wants and the pipe has ran dry. But could just be a story?

 

[Dale Sanders]

It's only £250 in screwfix.

 

[Harvest Fields]

Don't mean it is any good though mate.

 

[ShaunCorbs]

It's only £250 in screwfix.

cant go over 12 lpm so about the same you have now

 

[ShaunCorbs]

how you getting on dale?

 

[Dale Sanders]

Increased from 15mm to 22mm but no difference in flow. Had a plumber over and said a salamander home boost or an accumulator

 

[Vee]

Go for accumulator. Biggest volume you have space for.

 

[Dale Sanders]

Trouble is I keep going around in circles. Some say it won't work and others say it will.

 

[Vee]

Have successfully applied accumulator to system running only 8 lpm, to function withMegaflow. Look after other systems with this setup, working fine. About to install another accumulator system boosting from 22 lpm to 45 lpm at peak. I think for a lot it’s the unknown and sizing and adequate pressure is prerequisite. Consult accumulator manufacturer if in doubt. Otherwise the only other options for you is break tank with booster pump at low level or storage gravity fed at high level. There is no cheap and easy way to overcome this.

 

[ShaunCorbs]

Have successfully applied accumulator to system running only 8 lpm, to function withMegaflow. Look after other systems with this setup, working fine. About to install another accumulator system boosting from 22 lpm to 45 lpm at peak. I think for a lot it’s the unknown and sizing and adequate pressure is prerequisite. Consult accumulator manufacturer if in doubt. Otherwise the only other options for you is break tank with booster pump at low level or storage gravity fed at high level. There is no cheap and easy way to overcome this.

Your still only going to get 10 minutes with a 300l accumulator with two outlets open at 14lpm

And home boost can only do 12lpm which is what you have now

 

[Harvest Fields]

Your still only going to get 10 minutes with a 300l accumulator with two outlets open at 14lpm

And home boost can only do 12lpm which is what you have now

Think you have said this before mate!

 

[Dale Sanders]

Why are people on here tell me it will work and 2 different plumbers who came round told me it will work then?

 

[Harvest Fields]

Why are people on here tell me it will work and 2 different plumbers who came round told me it will work then?

We are not right all the time. The advice we give is based on our own knowledge base. In this trade what works for one property does not necessarily work in another. I for instance try to offer the best advice I can to a reasonable cost to the customer. You may fit an accumulator and you will be no better off at all. But I for one would like to know the outcome if you do manage to fix your issue.

 

[Harvest Fields]

We are not right all the time. The advice we give is based on our own knowledge base. In this trade what works for one property does not necessarily work in another. I for instance try to offer the best advice I can to a reasonable cost to the customer. You may fit an accumulator and you will be no better off at all. But I for one would like to know the outcome if you do manage to fix your issue.

My above post was supposed to say may be no better off at all.

 

[Last Plumber]

I have skim read this thread with there being 70+ posts so forgive me if I repeat anything that has been said.

Your Boiler will give 13 litres per min @ a 40 deg rise +/- 15%.

If you are testing the mains cold water flow rate at a tap, that does not mean the flow rate at the entry point on the Boiler will be the same. The standing pressure would be similar of course, (depending on how high the appliance is) but not the flow rate.

You will lose flow rate due to frictional resistances in the pipe work from the mains entry point in your property to the appliance. This may only be minimal.

I would ask the installer to test the flow rate beneath the Boiler and see what it is there. Then you can address whether the issue is a lack of flow or a problem with the Boiler itself.

There is a flow regulator inside these (erp version) and there is a strainer in the inlet.

If you want to run two taps you will be sharing the hot water from the boiler between them. There is nothing you can do about that with this Boiler.

Did you seek advice and discuss your requirements with Heating Engineers prior to deciding on a combi?
Unfortunately it does sound as though you have the wrong system for you. Even if the Boiler was delivering 13 lpm at 40 deg rise, it would still be unsuitable for you by the sound of it.

 

[Stigster]

I have always said if you have the required supply and room for an unvented cylinder, always install a cylinder. Combis are best for small properties with only one bathroom unless you can afford to go big kW and even then a cylinder will perform better in most circumstances. unfortunately OP doesn't currently have sufficient incoming mains flow and pressure to make an unvented cylinder work properly.

A 300 litre cylinder and an accumulator same size might do the job if there is enough pressure to charge the accumulator acceptably.

 

[Harvest Fields]

I have always said if you have the required supply and room for an unvented cylinder, always install a cylinder. Combis are best for small properties with only one bathroom unless you can afford to go big kW and even then a cylinder will perform better in most circumstances. unfortunately OP doesn't currently have sufficient incoming mains flow and pressure to make an unvented cylinder work properly.

A 300 litre cylinder and an accumulator same size might do the job if there is enough pressure to charge the accumulator acceptably.

But I am sure that Dale Sanders is on about pitting the accumulator onto there existing combi.

 

[Dale Sanders]

Yes so what I have been advised by the engineer who installed the system is if I want to increase flow I would need to add an accumulator, he is suggesting that i get a 240l mainsboost vessel with 22mm upstream system. I am being quoted £760.

 

[Last Plumber]

Yes so what I have been advised by the engineer who installed the system is if I want to increase flow I would need to add an accumulator, he is suggesting that i get a 240l mainsboost vessel with 22mm upstream system. I am being quoted £760.

Your Boiler will only give you 13 lpm at a 40 degree rise plus or minus 15%.

It does not matter what you connect it to, it will only give that.

If you think it is worth the money for the extra 3 lpm, that’s your choice of course.

 

[Dale Sanders]

If I get 13lpm then I'll be happy. At the moment I'm getting 9-10lpm.

 

[Last Plumber]

A 36 KW Combi, 240 litre vessel and £5670, to give you 13 lpm seems absurd.

Is this a DIY gone wrong ?

Sorry Dale but if it isn’t, you need to be asking for this to be put right without any further expense to yourself !

Surely the installer took measurements of pressure and flow amongst other things before doing the job ?

 

[Stigster]

But I am sure that Dale Sanders is on about pitting the accumulator onto there existing combi.

I know. The problem is that nothing OP does to his system will make that combi do what he wants. A good sized cylinder with a good supply (better than they have at the moment unfortunately) is surely the best way to achieve performance on two hot outlets simultaneously.

To fit an accumulator with its cost for the gain of 3 or 4 ltr./m of hot water performance is not worth it in my mind but it's not my money.

The only practical way I can see involves a cylinder.

 

[Dale Sanders]

Would that mean removing the the combi? I have already emailed the installer stating I am not happy. Just waiting a reply

 

[ShaunCorbs]

Would that mean removing the the combi? I have already emailed the installer stating I am not happy. Just waiting a reply

No you can fit a unvented cylinder on your combi but incoming flow and pressure is key

 

[Dale Sanders]

Ok. I have not even been given that option.
I will do whatever it takes but nobody is telling me a guarteed fix.
What do you mean about flow and pressure is key.

 

[ShaunCorbs]

Ok. I have not even been given that option.
I will do whatever it takes but nobody is telling me a guarteed fix.
What do you mean about flow and pressure is key.

For any system to work correctly over two outlets you need about 3 bar and 20lpm on your cold main

 

[Dale Sanders]

I feel like I'm going around in circles don't get me wrong I really appreciate all your help but I don't have 20lpm I have 14lpm mains in and I have 3 bar. What can i do to resolve my issue with lease hassle and expense. I cannot remove the combi as I'd prob have to take the engineer to court for that the happen. Cheers

 

[ShaunCorbs]

I feel like I'm going around in circles don't get me wrong I really appreciate all your help but I don't have 20lpm I have 14lpm mains in and I have 3 bar. What can i do to resolve my issue with lease hassle and expense. I cannot remove the combi as I'd prob have to take the engineer to court for that the happen. Cheers

If you only have 14lpm that's no good for an unvented or a combi esp if you want two outlets

If you want to increase your flow, note not really worth doing that on a combi as your stuck with x amount as there limited

Stuart Turner

But that system will only last around 10 minutes at full flow eg 15lpm etc

 

[Dale Sanders]

The only issue to flow time to fill the bath. If it fills the bath in the same time as my cylinder did I'm happy

 

[Frog67]

One sure way to remedy this problem...Alter the Combi to act as a system boiler and install open vented S plan system using cylinder and CWST.
The head of water from your CWST and Hot Water Cylinder will be equal and if the flow rates still are'nt good enough you could even install a shower pump.
As someone stated earlier in this post, Combi's are ok for small one bathroom properties but that is basically it.
I wonder how many people throughout the years have ripped out open vented systems only to regret it once they realise how much more restrictive pressurised systems can be.

 

[Chuck]

I wonder how many people throughout the years have ripped out open vented systems only to regret it once they realise how much more restrictive pressurised systems can be.

Pretty much everyone who's had it done I suspect...

 

[Dale Sanders]

So had another local plumber out and without turning on any taps he identified the issue straight away. There is a double check valve on the mains going into the boiler. He says that can restrict flow by a lot. Thoughts?

 

[ShaunCorbs]

Yep there's a couple of lpm why was it installed, doesn't need to be

Also needs a shock arrestor fitting at the boiler on the cold mains