Is the extra pump and thermostatic valve necesary with a condensing type gas boiler?

[eddie3000]

Somebody decided to close the my previous thread before I got a chance to answer back! I hope I didn't violate any of the forum's rules. If I did, I apologise.

But now getting back to the subject, everybody said I was wrong. Why? I did not expect to be "yelled" at in that manner. I was hoping somebody would give me a reasoned explanation, not just saying I'm wrong and that's it. My installer is just the same, he says that's the way it should be, but he is totally incapable of explaining why. That's why I think that he either doesn't know or he's trying to rip me off.

I still do not understand why I must have an extra pump and a thermostatic valve with the boiler I have. The extra pump is rated at 100W (exactly the same as my boiler's!). Two pumps in series aren't much help, are they?. My boiler has to hot water circuits. One for the heating and another for tap hot water. It has two independendent temperature settings for them as well. When you open the hot water tap it switches to hot water production mode, and when you close the tap it switches back to heating mode by default. That is why I do not understand why I need an extra pump in series with the boiler's, and a thermostatic valve when the boiler can produce water at 30ºC or less (it goes all the way down to 20ºC).

Thanks again, and I hope to get a clear answer this time.

 

[Unregistered]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

You're wrong

 

[Riley]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Phone whichever manufacturer your having installed they will explain it. Your installer is right. Basically you will not get suitable heat to your dhw which will prevent bacteria and legionella

 

[Riley]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Croppie!!!!!!

 

[rpm]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Croppie!!!!!!

Hold on a mo ...........
I want to know make and model of said boiler.

And as said why not call the UFH manufacture help line.

 

[jonnyswamp]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

The pump inside your boiler will only pump water around a standard heating system ie, pipe work and rads
It wont successfully pump c/h water around your system (rads etc) and your underfloor circuits (probably a few hundred foot of pipe work) this is why you need a second pump
Also the thermostatic blending valve is required as the u/floor operates at a much lower temp than your rads and the valve will mix the flow and return water to keep temp at a stable temp
Others on here can explain it far better than me, if you're still undecided, google is your friend

 

[Riley]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Ignore my previous post as I note you have a combi. All the same your pump on its own will not be man enough.

 

[eddie3000]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Thank you for your kind answers.

My boiler is an Ariston clas premium 35KW. It runs with natural gas. Just reading through the instructions it says something about a protection thermostat should be installed on the hot water outlet when using underfloor heating. This thermostat should be set to desired maximum operating temperature. It's function would be to shutdown the boiler if by any chance it happens to exceed the maximum temperature. On the other hand, if not installed, a thermostatic valve should be added instead. I haven't found anything about maximum tube length the pump can handle. So I guess I can do without the thermostatic valve if I have the protection thermostat. But I may have to add another pump. The system is not fully installed yet, but it will be having about 12 circuits of 100meters each on average. But I can't understand why a pump in series would do any good. I'd expect two or three pumps in parallel, each pumping three or four circuits independently would make a lot more sense to me.

 

[Riley]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

I'm out please just accept that it's needed mate. I'm not trying to fall out with anyone on here. There are literally 100s of years experience (FREE advice) on here telling you that it's required sometimes you need to just trust people. Your responses are essentially saying that you don't trust any plumbers so with respect you're probably not far from getting no responses. Contact the manufacturers. Not everyone is trying to rip you off

 

[eddie3000]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Ok. So I'm going to tell my installer to separate the whole house into two sections and to not install the thermostatic valve and install two extra pumps and two manifolds instead. That should work fine. The emergency shut-off thermostat costs around 4-5€.

It's not that I don't trust plumbers. I simply do not trust people who do not know what they are doing, specially when I ask them why they do something and they do not provide an answer. I get suspicious. Wouldn't you? I have not seen any underfloor heating with two pumps and no thermostatic valve on the internet and I've spent weeks looking around the internet before deciding whether I wanted radiators or underfloor heating. I was just hoping that the 100 years experience you say you have here would be a bit more scientific.

Thanks for your help. Sorry if I have wasted your time. Bye!

 

[Riley]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Good luck with it. Your plumber should get you to sign a disclaimer as you will not be happy. They only suggest no pump and thermostatic valve if the boiler is dedicated to the underfloor heating.

 

[rpm]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Bye.

 

[Plumbstar Tom]

Re: Is the extra pump and thermostatic valve necesary with a condensing type gas boil

Some people just don't want to listen.

Closed (again)