Mains fed combi boiler disaster

Sleeper12

Had a call out today to replace a leaking As2000xt power shower. I needed the hot press to shut off the hot water. Hot press was downstairs but no hot water cylinder. There was a newly fitted combi boiler. Unfortunately someone thought it a good idea to connect it to the mains supply instead of using a break tank and pump.

The mains pressure burst the power shower. Homeowner has two As2000xt showers and a T90. I couldn't connect a Triton Novel SR to mains pressure as it will likely pop from the pressure & the warranty would be void. Even taking a chance on this the thermostatic cartridge wouldn't be able to control the temperature as the cold supply is tank fed. The cartridge can't cope with the unbalanced pressure between the hot & cold. The other As2000xt is useless too. The "plumber" who installed the combi (& certed it) didn't know the difference between a power shower and an electric shower. He quickly became abusive on the phone and I doubt he will be back to rectify this mess.

I'm not getting involved in any of the work & I declined to install the shower. I'm thinking there was originally a feed from the cold water tank to the cylinder downstairs and this pipe must be blanked close to the boiler. it's simple enough to connect this to the boiler and remove the mains supply. A pump can be installed on the hot & cold supply coming from the attic tank giving balanced pressure. If he can keep the static pressure below or around 1 bar then a Triton Novel might be suitable but would one bar be enough for the rest of the house? I would imagine it a nightmare to try put pressure reducing valves on the hot & cold for each of the shower? With the attic converted & the hot press on the ground floor I'm not sure where you'd find the pipes to tap into for pressure reducing valves.

Homeowner feels he paid more than enough already for the combi boiler (1700 I think). I'm guessing it could cost another 1000 to supply & fit a decent pump and alter the pipework. Maybe more? I genuinely don't understand why anyone would consider connecting a combi boiler to the mains supply in Ireland. Connecting two Triton As2000xt power showers to the mains supply is the ultimate in stupidity. I'm feeling bad for the homeowners, a youngish couple. Any ideas or suggestions would be appreciated. I'd love to help them come up with a solution. I doubt original plumber will be back.

antoinolachtnai

You are talking about feeding the boiler from the roof tank basically? I would be wary of doing that, because it is directly interfering with the most expensive piece of plumbing equipment in the house, the boiler and is way outside how the boiler is designed to operate.

An alternative idea - definitely not a recommendation -. Pressure reducing valve at entrance to house set to give you one and a bit bar of pressure upstairs? Then plumb the cold water directly to the mains eliminating the roof tank and so allowing mixer valves to work?

Another route, and maybe this is the most practical thing: there is a fitting called a pressure equalising valve. You might be able to install this upstream from the AS2000XT's

https://www.bes.co.uk/water-pressure-equalising-valve-16711/

I do not have any practical experience of this solution but looked at them for a few 'situations'. I was lucky enough that I was eventually able to the problem 'properly' (in one case replumbed the previously-mains supply off the tank the hot was coming from, in another relocated a tank and linked it to the second tank).

Whatever you do, your customer is going to end up with a system which can't possibly comply with any standards anywhere, but at least has a chance of working.

The customer needs to understand in writing, up-front, that the existing system is not compliant and not functional, that what you are specifying is an interim solution which needs to be replaced with a proper solution at some point and that as such it doesn't comply with the building regulations and Irish Water requirements.

My only other suggestion is to ring the technical desk of whatever manufacturer or distributor sold this genius this boiler and talk to them in a friendly way, apprising them of the householder's situation and asking for their ideas. At the very least it will let them know what the guy is out there doing. They are unlikely to want to take any responsibility but they might at least give you some suggestions or advice.

Remember, you are the hero here. Don't let anybody make you the villain!

Sleeper12

antoinolachtnai wrote:

You are talking about feeding the boiler from the roof tank basically? I would be wary of doing that, because it is directly interfering with the most expensive piece of plumbing equipment in the house, the boiler and is way outside how the boiler is designed to operate.

You do understand that a combi boiler installed in Ireland should not be connected to the mains supply? The fitting instructions relating to the mains supply is for the UK. The fitting instructions will go on to say that it should be installed according to the local building regulations and bylaws. It should be fed by a break tank and a pump. It's the fact that this installer ignored the building regulations that has caused the damage

antoinolachtnai

Sleeper12 wrote: »

You do understand that a combi boiler installed in Ireland should not be connected to the mains supply? The fitting instructions relating to the mains supply is for the UK. The fitting instructions will go on to say that it should be installed according to the local building regulations and bylaws. It should be fed by a break tank and a pump. It's the fact that this installer ignored the building regulations that has caused the damage

Yes for sure. The problem is that if the householders won’t now pay for the proper break tank and pump then how is the whole situation to be fixed? No matter what they do it’s a mess.

Are you saying that in your solution the roof tank would be a break tank and would be pumped?

There is no question this genius has made a mess of it. The question As I see it is now how to fix it on a budget.

In the end they want it to (a) work (b) be compliant and (c) be cheap. They can have any two but i can’t see how they can have all three.

kenmm

Sleeper12 wrote: »

You do understand that a combi boiler installed in Ireland should not be connected to the mains supply?

Can someone explain why this is the case? Has the UK got some sort of minimum pressure that Ireland doesn't or something?

antoinolachtnai

The requirement in law is that you provide your own adequate storage.

The reason for this is firstly because there is no guarantee of (a) continuous service or (b) adequate pressure at the times when demand is highest. Secondly, use of storage tanks is supposed to spread the period of peak demand on the water system.

In the UK water companies are supposed to guarantee a certain pressure. In Ireland this is not the case.

Sleeper12

antoinolachtnai wrote: »

Yes for sure. The problem is that if the householders won’t now pay for the proper break tank and pump then how is the whole situation to be fixed? No matter what they do it’s a mess.

Are you saying that in your solution the roof tank would be a break tank and would be pumped?

There is no question this genius has made a mess of it. The question As I see it is now how to fix it on a budget.

In the end they want it to (a) work (b) be compliant and (c) be cheap. They can have any two but i can’t see how they can have all three.

Yes. I'm suggesting Cold water tank in the attic used as break water tank. Pump both hot & cold as it leaves the tank. This will pressurize the entire house & give equal pressure. Pressure can be limited to 1 Bar while they have AS2000xt showers but if they eventually change these to bar mixer then the pressure can be increased.The main downside is the toilets will be pumped so will make noise at night. In my mind the only solution is to take Combi off the mains altogether.


Have I missed something? Do you see an issue using attic tank as break tank?

kenmm wrote: »

Can someone explain why this is the case? Has the UK got some sort of minimum pressure that Ireland doesn't or something?

For the most part UK has far greater pressure than ireland. 10 bar wouldn't be unusual. In Dublin you are lucky to get 1 bar & less at peak times.



In the UK the combi is off the mains but so is the cold supply giving equal pressure. Thermostatic showers require equal pressure. Apart from combi boilers being connected to the mains being against building regs, bylaws etc it is bad plumbing & bad practice. I had a call from a lady in an apartment before that has to get out of the shower & go into another room & adjust the temperature of the boiler to change the temperature of the shower. The showers thermostatic cartridge couldn't adjust the tempeture.

Idbatterim

Where in ireland is the pressure high enough to do that damage? The mains pressure here in general is laughable

rightjob!

Sleeper12 wrote: »

Had a call out today to replace a leaking As2000xt power shower. I needed the hot press to shut off the hot water. Hot press was downstairs but no hot water cylinder. There was a newly fitted combi boiler. Unfortunately someone thought it a good idea to connect it to the mains supply instead of using a break tank and pump.

The mains pressure burst the power shower. Homeowner has two As2000xt showers and a T90. I couldn't connect a Triton Novel SR to mains pressure as it will likely pop from the pressure & the warranty would be void. Even taking a chance on this the thermostatic cartridge wouldn't be able to control the temperature as the cold supply is tank fed. The cartridge can't cope with the unbalanced pressure between the hot & cold. The other As2000xt is useless too. The "plumber" who installed the combi (& certed it) didn't know the difference between a power shower and an electric shower. He quickly became abusive on the phone and I doubt he will be back to rectify this mess.

I'm not getting involved in any of the work & I declined to install the shower. I'm thinking there was originally a feed from the cold water tank to the cylinder downstairs and this pipe must be blanked close to the boiler. it's simple enough to connect this to the boiler and remove the mains supply. A pump can be installed on the hot & cold supply coming from the attic tank giving balanced pressure. If he can keep the static pressure below or around 1 bar then a Triton Novel might be suitable but would one bar be enough for the rest of the house? I would imagine it a nightmare to try put pressure reducing valves on the hot & cold for each of the shower? With the attic converted & the hot press on the ground floor I'm not sure where you'd find the pipes to tap into for pressure reducing valves.

Homeowner feels he paid more than enough already for the combi boiler (1700 I think). I'm guessing it could cost another 1000 to supply & fit a decent pump and alter the pipework. Maybe more? I genuinely don't understand why anyone would consider connecting a combi boiler to the mains supply in Ireland. Connecting two Triton As2000xt power showers to the mains supply is the ultimate in stupidity. I'm feeling bad for the homeowners, a youngish couple. Any ideas or suggestions would be appreciated. I'd love to help them come up with a solution. I doubt original plumber will be back.

Initial installation price is way too cheap,

Prob the only way to put it right is to remove both power showers.(one is useless as burst)
Instal two standard t-bar showers instead of the power showers.
Install a booster pump to feed the hots and colds.

Definitely will be some messing with tiles ect but its either deal with showers splitting or put it right and move on.

Sleeper12

rightjob! wrote:

Prob the only way to put it right is to remove both power showers.(one is useless as burst) Instal two standard t-bar showers instead of the power showers. Install a booster pump to feed the hots and colds.

So you are talking about removing the mains supply to the combi and using the cold water tank in the attic as break tank?

rightjob!

Sleeper12 wrote: »

So you are talking about removing the mains supply to the combi and using the cold water tank in the attic as break tank?

Yes remove the mains into the combi, take a feed off the attic tank into a pump and then that into the combi for hots and tee off for colds.

At least then they have a guaranteed pressure for the combi.

Change both power showers for exposed t bars.

No use saying it now and im sure the customer wasn’t aware at the time,but €1700 for a combi install it was always going to be a disaster.

Dtp1979

rightjob! wrote: »

Initial installation price is way too cheap,

Prob the only way to put it right is to remove both power showers.(one is useless as burst)
Instal two standard t-bar showers instead of the power showers.
Install a booster pump to feed the hots and colds.

Definitely will be some messing with tiles ect but its either deal with showers splitting or put it right and move on.

Pretty much what I was gonna say. Absolute joke he got a combi fitted for 1700 too

Dtp1979

rightjob! wrote: »

Yes remove the mains into the combi, take a feed off the attic tank into a pump and then that into the combi for hots and tee off for colds.

At least then they have a guaranteed pressure for the combi.

Change both power showers for exposed t bars.

No use saying it now and im sure the customer wasn’t aware at the time,but €1700 for a combi install it was always going to be a disaster.

Absolutely the only way to rectify this.

antoinolachtnai

rightjob! wrote: »

Yes remove the mains into the combi, take a feed off the attic tank into a pump and then that into the combi for hots and tee off for colds.

At least then they have a guaranteed pressure for the combi.

Change both power showers for exposed t bars.

No use saying it now and im sure the customer wasn’t aware at the time,but €1700 for a combi install it was always going to be a disaster.

I think that is a good solution if you can get them to pay for it. All the bits add up. I have seen the thing with a pump in the attic. The issue is noise as you say, though maybe cold water could be gotten flow at night if the pump and combi were turned off, with a time switch? Maybe you could locate the pump away from the sleeping areas. Maybe there is a way to have the pump down beside the boiler?

Labour in an attic is obviously no fun and everything takes longer. Might be as well to get a new tank and put it downstairs? All swings and roundabouts I suppose.

I hope they appreciate your efforts to come up with a good solution. Very tricky situation.

Dtp1979

antoinolachtnai wrote: »

I think that is a good solution if you can get them to pay for it. All the bits add up. I have seen the thing with a pump in the attic. The issue is noise as you say, though maybe cold water could be gotten flow at night if the pump and combi were turned off, with a time switch? Maybe you could locate the pump away from the sleeping areas. Maybe there is a way to have the pump down beside the boiler?

Labour in an attic is obviously no fun and everything takes longer. Might be as well to get a new tank and put it downstairs? All swings and roundabouts I suppose.

I hope they appreciate your efforts to come up with a good solution. Very tricky situation.

Submersible pump in the attic tank. Obviously kept an inch off the base and held with bungee cords or stronger. Flexible 1” metal hose off that. Barely any noise from it.

rightjob!

Dtp1979 wrote: »

Pretty much what I was gonna say. Absolute joke he got a combi fitted for 1700 too

Guaranteed its an ideal logic,no filter or flush,taken off the mains and the hot is 1/2pex going back onto the hot under a sink.

Sleeper12

Dtp1979 wrote:

Pretty much what I was gonna say. Absolute joke he got a combi fitted for 1700 too

I agree. He got what he paid for. In fairness to him no one explained why this quote was cheaper than the rest. They are a young enough couple with young kids. It's the first boiler he's ever gotten changed. He thought the RGI cert meant the whole installation is up to code and not just the gas safety end of it. It's an expensive mistake on his part. I've seen hundreds of installations like this. What makes this worse than the rest is that the plumber didn't look today see what the boiler was feeding and if mains supply was suitable for these. His installation directly caused damage to the power shower.

If attic tank becomes break tank and hot & cold are Pumped from this reduced to one bar, will this be su pressure for the combi to run smoothly and do what it's supposed to do?

rightjob!

Sleeper12 wrote: »

I agree. He got what he paid for. In fairness to him no one explained why this quote was cheaper than the rest. They are a young enough couple with young kids. It's the first boiler he's ever gotten changed. He thought the RGI cert meant the whole installation is up to code and not just the gas safety end of it. It's an expensive mistake on his part. I've seen hundreds of installations like this. What makes this worse than the rest is that the plumber didn't look today see what the boiler was feeding and if mains supply was suitable for these. His installation directly caused damage to the power shower.

If attic tank becomes break tank and hot & cold are Pumped from this reduced to one bar, will this be su pressure for the combi to run smoothly and do what it's supposed to do?

Should do,but pressure reducing valves can end up way above the set pressure for no reason.

So you couldn’t rely on them as the consequence is another shower bursting and a flood.

antoinolachtnai

rightjob! wrote: »

Should do,but pressure reducing valves can end up way above the set pressure for no reason.

So you couldn’t rely on them as the consequence is another shower bursting and a flood.

And you would be putting the pressure reducing valve in front of a pump. Are the pump and PRV designed to be used in this way?

Sizing the pump appropriately is obviously going to be critical.

Dtp1979

End of the day, manufactures instructions will state that these showers cannot be fed from a pressurised system. Therefore whoever fits these pressure reducing valves will be liable when they fail and flood the house

Dtp1979

End of the day, manufactures instructions will state that these showers cannot be fed from a pressurised system. Therefore whoever fits these pressure reducing valves will be liable when they fail and flood the house

rightjob!

antoinolachtnai wrote: »

And you would be putting the pressure reducing valve in front of a pump. Are the pump and PRV designed to be used in this way?

Sizing the pump appropriately is obviously going to be critical.

Be no point in an one bar pump,best way is to set the combi up properly and change the showers.

Could guarantee that if you keep the power shower and boost the combi it will end in a disaster at some stage and you will be back to square one again.

antoinolachtnai

You are right. There is no shortcut here. It's all just deferring the awful day.

Sleeper12

Dtp1979 wrote: »

End of the day, manufactures instructions will state that these showers cannot be fed from a pressurised system. Therefore whoever fits these pressure reducing valves will be liable when they fail and flood the house

They can be fitted to a pressurized system but must have a maximum static pressure of 1 bar. They can't be connected to the mains supply though. Ugly sticker on each one stating not to be connected to mains pressure