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Combi boiler with no pressure and sporadic hot water

Posted by j m, on
It's a long story and I will try to summarise in bullet points: -I needed to replace an old boiler and was given two quotes -I went with the combo boiler option as after reading online, it seemed the best option for the small flat -the boiler was fitted and immediately I noticed that the once wonderful shower, now had no pressure and that the hot water was sporadic -when approached, the plumbing firm said that they had removed the pump as it was not compatible with the combi boiler. This was not quoted for and was not authorised at any point. If I had known either before or during the work, I would have chosen the non-combi option which is compatible with a pump. -Four months on, I am still trying for a resolution but the one they are now giving through their guild is what I asked for originally and the co. said it was 'unsafe and would pollute the water supply'. How is it now safe? Please can you advise if this will work and why their suggesting it means it is safe, when it wasn't when I suggested it...? I only want to know that it is alright and that it will not start another set of problems. To reinstate the pump: Drain down the system Take hot water feed from the boiler to the kitchen tap Reinstate original cold to feed cylinder Run flow and return from the combination boiler to feed the cylinder to supply hot water for the shower Re-instate the original pump Supply and fit 2 x 2 port valves to operate both heating and hot water Supply and fit a new timer clock Supply and fit a new cylinder stat This has caused me so much stress and money, not to mention devaluing my home as a result of the ineffective bathroom. I am desperate for it to be resolved. Fitting an electric shower has also been suggested by others but I have a very expensive shower, which was brilliant. Also, would that be more powerful? Would it solve the problem of hot water dropping out mid shower? Thank you in advance for any help
gareth butcher

gareth butcher

Hi there. Unfortunately you seem like you have had a bad experience with this plumbing firm due to bad advice. They should of originally advised you to keep the system you had with the pump and tanks as no combi would really ever match the flow of hot water if you had a good quality pump. What they have now quoted for seems fine but at the same time a waste of time and money.
William Keogh

William Keogh

J, To raise points about the Combi Boiler Water Pressure; It is your mains Pressure combined with Hot Water Flow Rate that will give you a decent pressure with consistent Hot Water; 1) It could be your Cold Mains pressure is too great and may need a Pressure Reducing Valve Fitted 2) Or you water pressure is not sufficient which means a Mains Booster 1.6 Bar to be fitted To raise points about the Combi Hot Water; 1) It sounds like the Combi Boiler fitted maybe only has a small flow rate of Hot Water and a larger Combi should have fitted. Other Points; 1) They are correct you cannot have a pump attached to a Combi System 2) It is not advisable to fit a pump to a Combination Hot Water Cylinder either due to insufficient Head of Water Held unless you have a separate Hot Water Cylinder and Cold Water Storage Tank minimum 60 Galleons. 3) The refitting of Hot Water Cylinder, valves, etc. is fine, as long as they have a mechanism that will turn of Combi automatically if no Heating Demand is necessarry, e.g. No Heating required but Hot Water to be heated and reaches temperature, then a mechanism that instructs Combi to turn off, otherwise the pump will continue running in the Combi with no where for the water to circulate unless they fit a Bye Pass loop. So, I would not go down this route if it was me has Combi not designed to work like a Heating Only Boiler. If I was you I would persist with them to ascertain enough Mains Pressure to operate Combi correctly and that the minimum flow rate of the Combi for Hot Water is 12 litres per minute at 55 degrees Centrigrade. The mistake people make when fitting a Combi is not to consider Hot Water demands and thus usually fit a Combi that will do Central Heating adequately, but to get customers Hot Water Demands it may be necessary to increase Combi size by another 5kw to allow for this. Hope this helps, Bill Pipe Dreams Plumbing Services Bournemouth (we can be found on Google under Plumbers Bournemouth)
Iain McAlpine

Iain McAlpine

Hi When you fit a combo you have to remove the parts the company have done, your problem might be that your cold water to the bathroom is from storage and not the mains which might be the result of your pressure problem, ask if this has been done but you should have good pressure at your shower with a combo Iain
Phil Lipscombe

Phil Lipscombe

1] I assume that the flat is two to three of ground level. if this is the case it is debatable if an electric shower will work 2] a shower pump is not designed to run of mains water and is against the water regs therefore not safe you don 't say how many flats in the block with out a site its not worth commenting further

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